For fans of the show, especially who are getting all twitchy waiting for the return in the new year, there is an excellent Wiki out there with so much detail it will make you pull out your collection of .avi files that your brother was nice enough to put on a DVD for you and re-watch the whole damn thing again in one sitting. Again.
e.g.
http://heroeswiki.com/Category:Powers
Enjoy!
For those who have seen all the eps and/or the graphic novels, there are a couple of sites listing a complete and detailed timeline, as a reminder of sorts...
http://heroeswiki.com/Timeline
http://www.9thwonders.com/boards/index.php?showtopic=22422