http://www.wastedyouth.org/ - This is a good source, but they are going through some construction on their site right now, but DEFINITELY keep this one bookmarked...
http://www.studiolina.com/tutorials/main.asp?sect=psp - This one is a good one as well...
However there are a few books I would Recommend...
- Photoshop 7 WOW Book by Jack Davis - Awesome techniques!!
- Photoshop 7 Down & Dirty Tricks by Scott Kelby - This is a great resource as well...
- Photoshop Photo Re-Touching Secrets by Scott Kelby - This has some great photo techniques...
I hope this helps...
Other than that I would suggest looking at about.com and doing google searches...