Joe McNally - a true photo-god:http://www.joemcnally.com/
Strobist.com - David Hobby's source for learning lighting:http://www.strobist.blogspot.com/
Flickr strobist group - great discussions on all things lighting:http://www.flickr.com/groups/strobist/
Dave Black - excellent online workshops:http://www.daveblackphotography.com/workshop/index.htm
Brian & Mallory - wedding pros:http://www.aviaphotography.com/
Al Jacobs - veteran event shooter, maker of the "Black Box" battery and a wonderfully witty writer. His wedding photographers guide (downloadable PDF) is a must read:http://www.aljacobs.com/
If you can't learn from those guys, you don't need to learn anything.