With all of these you could pretty much sum it up as, "If it's done right, it'd be great". Thus far, few hollywood people have figured out what exactly that entails.
Bioshock would make a pretty cool movie, so long as they take their time and play up on the mystery of Rapture. Like in the game, you see some action early on, but the focus is marveling at the city, gaining a sense of dread as you move deeper in, and slowly getting hints of the worse events that are to come (preview of the big daddy fight = awesome). I can see them getting too tempted into the thought that people would get bored quickly and shove a bunch of meaningless action in your face. Also, the first plasmids should be a moment of terrifying drama, and would have to be used sparingly and wisely. Not all of them would likely make it into the movie (though dear god I hope they include the bees! BEEEEESSS!! /zim).
Fallout 3 itself would NOT make a good movie, ever. A huge part of the game is feeling like it is YOU out there in the waste...and obviously they cannot have both the male and female lead and keep to the same story. They could easily work with the same general storyline and evil forces to create a new plot with new main characters. I can readily picture the first scene where the hero (who I think should be female...a contrast to all the gritty male apocalypse survivors out there) comes across feral ghouls for the first time.
Link spoke plenty in all of the manga comics, and it felt perfectly natural and, in fact, gave a unique new insight to the storylines of the games. He felt more real and human (hylian?), and I felt that it broadened his character, rather than the opposite (most folks are terrified of a speaking Link). For a story, however, I think they would need to create a new storyline that kinda sums up all of the best games. I strongly feel they should keep the relationship between Link and Zelda from Twilight Princess (strong, stoic princess, knight protector, NOTHING more) and have a separate love interest (Midna was cool at the end, but I do not think a movie about a werewolf Link would fly). And someone needs to tell Ganon that turning into a giant pig monster NEVER helps anything. Seriously.
I am not as familiar with some of the other games, but I agree with others that a Half-Life movie SHOULD be made someday soon, I'm just not sure how. Like with Link, I don't think a talking Gordon Freeman would be the end of the world...so long as he isn't a chatty dork.

It's easily possible to tell the movie from the point of view of someone else, but in order to understand the universe I think they'd have to do the story from the first game...and who else but Gordon could we follow? I always pictured him as a reluctant hero, but as he appears so confident and stoic in the artwork, I'm not all that sure who he really is. Maybe if they add a touch more characterization to him in Episode 3 it will be possible. Otherwise, it's too hard to picture.
/Rambly