There still seems to be a consensus amongst non-gamers that videogames are a waste of time and have no educational value. When I look back at my gaming history though and what I know, I find that I've learnt quite a bit from games; from history, physics & reading skills to mundane things such as how to cook the perfect runny egg (thanks Hideo Kojima).

What practical things or knowledge have you learnt from playing games?

Civilisation's Civipedia is a pub quizzer's best friend!

Might and Magic 2 taught me the words "inventory" and "disposition" when I was a wee lad.

APM performance does freaking matter, especially in RTS games.

The English language, more or less.

Playing just one more match in Starcraft is more important than having a life.

That contrary to popular belief even Italian plumbers get suicidal sometimes despite ones best efforts.

cheaters will always win

Same for me. Gaming really helped and motivated me in that sense.

Everquest: how to type well

I knew the basics from a short class I took, but EQ helped me type quickly and accurately. That's really been a help in my work as well.

^ hehe you too?

I recently reinstalled all 15 thousand expansions and what not, and forgot how to get quests and what not lol

Side note: I told my wife if I ever mentioned EverQuest after we got married that she should slap me in the face and take my credit card until the feeling past. I can't get sucked back in (although I've wanted to a few times).

So, in relation to the OP, I guess gaming has also taught me an ounce of self control (or at least knowing when I don't have any).

Games taught me English. Here's a related horribly google translated, brand new news article thing: Thing
The translation is hilarious, but the gist of it is that "play video games -> better English grades" is now science or something.

I learnt all I needed to pass my Japanese-language written driving test.

My first time as "co-pilot" in a plane was very different to everyone else's in the group I was in - because of me playing on flight simulators.

Apparently you didn't get the controls until the second time flying, be passenger to aerobatics until the third or do the aerobatics (as in, control them) until the fourth.

I got to do all three on my first flight :) The pilot was confident I knew what I was doing because I answered all the questions he asked me (naming various parts of the plane, how they work, how to execute various maneuvers etc.). He was ready to take control back at any moment because, obviously, simulator != real life but he never had to.

Learned to appreciate the forces that happen during the aerobatics and that controlled stalls are very strange to experience.

Adventure games taught me how to read. Not fully, but they were instrumental in my early stages of learning.