Here's a link to the Ghost Master Plasm and Ghost Editor.
THIS IS NOT MY WORK!
I just stumbled on it, tested it out to see if it worked, (along with checking it for any questionable things)
and it works just fine.

If anybody has problems with it, I'll edit my post and remove the link.

With it you can change all of your ghost's Tethers/Fetters, you can also edit the amount of Gold Plasm you have
(in order to teach your ghosts new spells) and you can change the spells that each ghost has.
So, if you picked a crappy spell/power for one of your ghosts (flower power comes to mind), simply change
it with the editor.

I've tested it out with the gog.com version 1.0.20.4 and the "All Ghosts" patch too, and it works just fine,
I'll make the standard DISCLAIMER that you SHOULD however, make a backup of your save games "just in case" something goes wrong.

I used one of my save games where I only had 791 Gold Plasm, and gave myself 15,000 Gold Plasm (It doesn't buy a whole heck of a lot when you've only got the higher level spells left to buy), and it worked just fine,
I was able to quit and exit the game, load it back up and click "Continue" and the amount was correct.

Anyway here's the link, and since it's an Angelfire link, I'll link to the page rather than the download,
because that might save the page some bandwidth instead of a straight link, (maybe?)
[url=]
http://www.angelfire.com/planet/zzzzsleep/[/url]
reason for edit: spelling

Fixed link.

Edit: But the link is no longer available.

This link works as of today, 7/30/2014

[url=]http://www.angelfire.com/planet/zzzzsleep[/url]

Cut and paste the link into your browser; the jump link doesn't work.