The positive effects of video games

I was thinking that this might be a fun topic - in which ways would you say that video games could have positive effects, apart from the pure joy factor itself?

Personally I have always felt that space shooters seem like a great way to practise your reflexes, since those kinds of games tend to require very fast reactions and an ability to make quick decisions (anyone who has played "Gun Nac" on Expert difficulty with ricochet bullets knows what I mean).
Also, tricky puzzle games such as "Solomon's Key" should be fairly good problem solving practice, since that game does require a lot of planning ahead and making preparations in various somewhat confusing ways.
It would also make sense that strategy games like "Final Fantasy Tactics" improve your strategic thinking, kind of like chess but in a slightly different way.
And games like "Metroid" for the NES should improve your sense of direction and your ability to remember locations in space.

What do you think about this?
And how much of an effect do you think it could have?
For example, could you decrease the risks of getting slow reflexes at an old age by playing fast-paced space shooter games several times a week, assuming that you don't become overly familiar with the exact attack patterns in those games?
Because I have noticed that I always become a lot more alert after I have played "Gun Nac" on Expert difficulty for an hour or something like that - it does have a rather pleasant after-effect, kind of like a reaction time workout.
I fully believe that this could have improved my reflexes quite a bit over time - I mean, it would be strange if it hasn't had any effect at all.

I don't want this to turn into tl;dr or TMI territory, so I'll try to keep it brief. I'm riddled with social anxieties I do my best to hide. I hide them in various ways and deal with them in various ways. Anyway, gaming helped me a lot to break out socially. I started out with co-op, then moved on to MMO's. I'm very different now at 30 than I was at 20, and a great deal of that has to do with games forcing me out of my comfort zone. :)