CVG has written up an extensive preview of BioShock, based on what they saw of the sci-fi RPG during a recent demo given by Irrational Games' Ken Levine.
There are over 50 passive powers available, with a huge range of functions. One group, for example, focuses on ways that you can manipulate your enemies. So, the 'Security Beacon' ability allows you to turn security turrets and cameras against the monsters instead of you, while 'Berserk Rage' sends enemies into a mindless fury, attacking other creatures. Another set, when combined, makes you a better hacker, so you can open locked vaults, subvert the security system and lower prices on ammunition.
Or you can perhaps lean toward powers that improve the physical characteristics of your character, giving you more health, more speed and better stealth.