Choosing a Field of View for a game is tricky - basically a trade off between 'how good it looks' and 'how much the player can see.'
Unless your player is sitting really close to the monitor or television, the typical field of view computer games used to use (often around 90) - doesn't look right. It looks like a fisheye lens. I think Halo was the first game I noticed that dramatically narrowed the field of view, not only fixing the perspective but giving it a more filmic look. Characters look taller and more heroic. When the field of view is narrower, things you're looking at look wider-and-taller, which is great for feelings of verticality and height. If you're falling or strafing, it feels like you're falling or strafing fast, as those large surfaces move past you. (But if you're moving forwards, away from the camera, it feels like you're moving not-so-fast.)
The problem with a narrow field of view is you can't see what's around you. Humans have almost 180 degrees of peripheral vision, and in real life have great situational awareness. When you narrow the field to 50 degrees or so (I think what Halo is around), it's like wearing blinders. And makes the games harder to play.
Spider-Man 2 had a very wide field-of-view, and always looked fish-eyed. But we needed it to play. Because you can move so fast and erratically, we had to keep the FOV wide so you could see as much as possible of what was around you.
So. Dynamic field of view. The first game I remember doing this was Burnout. When you go faster, the field of view widens, and it gives you this sense of extra acceleration and speed. So I did it for Energy Hook and it's the best of both worlds - that filmic heroic buildings-are-tall-I'm-really-high-up feeling for when you're walking around on buildings (or falling off of them), good peripheral vision for when you're swinging around and need it, and that extra sense of speed and acceleration to boot.
@JakubKoziol recorded this footage for us because the framerate starts to suck on my Mac when recording. And @RodeoClownII was the one who talked me into doing Wolfire-style voice-over on these things. (It's really time consuming - I kept doing more takes. I'm not going to try so hard next time.)