this has nothing to do with sites per say, but it is along the lines of recomendations:
i just read a great security book you should all own "The Penetration Testers Open Source Toolkit" (Syngress)
as for sites:
infosysec.com remote-exploit.org milw0rm.com sysinternals.com (the discussions and videos from Mark about the in-depth workings of Windows are an immense resource for learning)
iExploit.org seclist.org hackthissite.org (probably not now but still a good site for curious noobs) hackforums.net (when you wade through all the absolute shite on there thers a few good tuts) opensc.ws/opensc.ru [or whatever it is now] (good for malware coders, wouldn't hang around long tho :P) exploit-db.com (obvious) http://www.securitytube.net/ (some excellent vids) http://www.corelan.be:8800/ (the guy knows his shit)
There's loads more i've visited etc but those are the mainstream hacking sites i'd mention.
i have not been on milw0rm in ages so i wouldn't know! as far as infosysec, i have not been to that one in years, either, but that was at one time one of the most comprehensive security sites on the net. how bout phenoelit? is he still doing his thing? he was the pioneer when it came to advanced hacking concepts (especially internetwork attacks)
not at all a hack site, but the CISCO site in the tutorials/learning section (CCO?) is unsurpassed when it comes to basic network/protocol knowledge