So, as a veterian TA player I decided it would be a good idea to try to make a list of some of my personal favourite TA mods for anyone who buys this great game. So here is my plan, I will list some mods, give them a short description and a link to them.

Keep in mind, some of my mods I meantion may not have links to direct sites as some are out of production...

TA Spring
Some may now days require the 3D TA engine "Spring" found here. It is a 3D engine that slowly seperated itself from TA. My main highlight here, due to springs ablity to allow users to fully control units in FP... it allows you to personally control your krogoth in battle, which is bloody awesome.

http://springrts.com/wiki/Download

TA3D
Another 3D TA engine, while it is still in alpha and does not seem to have the mod support of Spring, it is a lot more true to TA and may be more enjoyable to purists. I prefer it to spring due to its full compatablity with skirmish.

http://ta3d.org/home-en.php

TA Mutator
an awesome mod manager which, unfortunatly I could not find an active link. It allows for quick swapping of mods and its own special gameplay tweeks called "mutators"
Info Link - http://www.rakrent.com/rtsc/html/tam.htm

Absolute Annihilation -

This mod was HUGE. It added a bunch of units before being ported to Sring and Abanadoned.

From the Readme File of v5
"Main Features:

- 100% conflict-free
- 110% stable
- Sexy new "glowy" textures
- 510 Units
- 252 Weapons
- Includes improved and customized Banzai 3.0 AI
- Includes latest TAMEC 2004 "Final" HPI sets
- Includes Dark Rain's map selection GUI
- Includes Gnome's MP lounge GUI
- Mac-compatible audio (should be)
"
There is no Defalt TAM version of this
Meaning to run this with multiple mods, you will either have to swap out the rev31 files, or do the following.
- Making AA TAM compatable (based on my v5 installer)
1) "install" AA to a temp folder
2) Rename the "Rev31.gp3" file in the AA instal NOT IN THE TA DIRECTORY to
"][AARev31.gp3"
3) Create a new text file called "][AA" but instead of saving as a .txt, save as .tc
4) Open the new file "][AA.tc" in Note pad and paste in the following
"TA Absolute Annihilation
## taAA
TAAA
][AARev31.gp3 rev31.CCX
"
Exactly as shown inside the "".
5) Move "][AARev31.gp3" and "][AA.tc" into your TAM install TC folder. "GOG.com\Total Annihilation\TA-Mutation\TCs"
6) Copy the "guide50" folder into your base TA folder "GOG.com\Total Annihilation" (not sure if this is needed needed, but I did it)
7) Run TAM, TA Absolute Annihilation should show up as an activatable and working mod!

THE PACK
This pack is another major unitpack for TA. Obviously it can not be used WITH any of the other unitpacks here, such as AA, but it is interesting to have more then one.

http://thepack.tauniverse.com/downloads.shtml

TA Escalation
While I have not played this modpack personally, chances are I will download it soon enough as it looks swanky. This new 2010 made mod seems to be focused on adding Supreme Commander Style units into the game, Drastically altering gameplay as a whole with a high quality mod. Supcom concepts like Shields, High End Experimental Units, Adjacency Bonuses, GUI updates and Upgradeable buildings being among the huge list.
This pack is more about quality then quanitity however, and has substancially less new units... however it is in beta so who knows what the future holds

http://taesc.tauniverse.com/?p=downloads

Updated: TA: Zero (Was TA Excess)

Another new pack, currently in alpha TA Excess plans to completly overhaul TA with new unit graphics, a new faction, and some brand new super units. As of now, it is really just a proof of concept mod, with only the lower teir units completed... awesome none the less so check it out. Looks like the most recent update has started to add T2 units, should be interesting to see where this mod goes.

http://zero.tauniverse.com/
http://zero.tauniverse.com/ta-zero/

Other mods which I cant find links for that are still active, but you may see around..

Talon Race Mod
This mod adds another brand new team to play with. Though a lot of the concepts seem to be reused in Escalation, it is worth looking at this mod.
http://www.moddb.com/mods/talon-race/downloads/talon-v103

"Command & Conquer TA"
an attempt at porting C&C into TA. Its rather funny, but a neat little mod to glace towards for a bit.

"TA Dune"
same as above, but for dune. Cute really

Starwars TA
A nice little mod that has since migrated over to spring. It is worth trying to find as it really adds to the game

"Final Frountier" This mod, predominately now days on Spring, was awesome. It moved TA to space, but I could not find an active link to the non-spring version so I didnt post.
Edit : http://zwzsg.hosted.luckz.de/TAFF/web/files.htm working download

TAUCP
Posted Below by bhxob on page 1. Can't belive I forgot this gem. This nice little unit pack adds some more spice to the game, not my FAVOURITE unit pack, but pretty darn spiffy.

Windowed TA
Okay, so this isnt really a mod... who cares. If you want to run TA windowed, make a shortcut to TA with the "-d" extension. Change the rez as you normally would, but the size does not change till ingame.

TA- Devolution
http://www.moddb.com/mods/total-annihilation-devolution
Another one I havent played yet, but it looks rather good. A new version was recently released so it may be worth looking at.

TA Mayhem
A great looking new mod mentioned on the second page. Still havent had a chance to play this but it really does look worth your time. Has spider construction bots for one,

http://www.moddb.com/mods/total-mayhem

Its a shame so many old and awesome TA mods are dead in the water, but some of these new mods look pretty awesome. Apart from these unit packs, remember you can find websites that stock individual units... which means that you can make your own personal unitpacks for use. The best thing about downloading unitpacks however is that these behelmoth packs are often well balanced and of higher quality then single units.... really TA has had such an active fanbase for years just look around for yourself, you will find that this short post is meirly a "tip of the iceberg" situation. Anyone have any other mods? feel free to post them for others benifits here.

Keep in mind, not ALL of these mods have been tested with the GOG version yet, so I dont know if they will all work. But its good to have a list I figure

if you like it, up rate my post. As you can see I dont post enough to have high karma lol

I rate up all this kinda stuff. I'd rate it twice if I could. ;)

Thanks! Ill be adding more mod names and links as I remember them

You're doing god's work. I rated you up again haha

The only thing I can add here is a something I have posted elsewhere.
http://files.tauniverse.com/fu/Files/TotalAnnihilation/Mods.aspx
There's quite a lot to go through there, for people wanting to look through some mods and maybe describe them for the rest of us.
If I knew what most of those mods were, I would comment on them, but I only have any past experience with TAUCP:
TAUCP
- Contains Over 230 3rd Party Units from various unit groups.
- Conflict free and 99% bug free gameplay (nothing is 100% bug free)
- Incorporates Switeck's TA Bugfix Version 1.6
- More Balanced Gameplay with 3rd Party Units
- Includes a Frontend Utility to enable/disable TAUCP, to select the AI to play against,
to set the starting metal & energy (can be more than 10000 metal/energy!) and to
select which unit pack sections (land, sea, air, etc) that you want to play with !
- Includes a user friendly Installer to ensure smooth installation of the Unit Pack
- Incorporates Switeck's Mostly Harmless AI Version 13 (don't let the name fool you!)
and Banzai 3.0 by M. Kenyon
Full Description/Readme
Unit Descriptions
Download

I just worked out how to make non-TAM mods work on TAM by applying instructions found on the "TA Escalation" page... Should I post a guide? Screenshot as proof of AA working as a TAM when previously it was not TAM capable.
and yes, all mods seem to work perfectly on the GOG version, at least, all ive tried have

Sure, more info/mods the better.

its a shame I dont have a proper rapidshare account, I tried to upload my version of TAM up but it said "10 downloads left" and I figured that wasnt too good.

I still have the TA Mutator 1.02 beta installer package handy, if anyone wants it. Was there a non-beta version?

I have a copy too, and no, the only "non beta" version was older then the beta version

Here is a link I found on another post that should have most, if not all, mods that have been mentioned.
http://files.tauniverse.com/fu/Files/TotalAnnihilation/Mods.aspx
Sorry, I didn't see you'd already posted my link. Good work.

TA: Spring doesn't appear to be a mod itself, but a standalone engine. It mentions that you have to install the engine first then install the games to the engine. How do you do that with the original TA, and in particular the GOG version? Is it even possible?

I love UTASP. I still have an original TA+CC+BT install modded with UTASP on my harddrive. I've copied it to all my PC's in the last years, because UTASP, for me, is the ultimate version of TA.