Power cards are a nice way of keeping the relevant information for your character handy, without having to copy out your power texts or use up a ton of scratch paper (not to mention the time spent trying to decipher your marks from the previous session). There's some nice ones out there on the net, and I believe WotC sells some too. Having them in an electronic format is nice (not sure if WotC does that), since you can just print out the ones you need and can make copies if there's more than one character with the same power.