Well, theres tons of sites out there, you can use google to find a lot of them.

Heres couple of good links

The New UGN Security Archive (doesnt have a lot yet, still underconstruction sorta = ) )

http://archive.undergroundnews.com

The Old UGN Security KBase has tons of things you can learn from, it also has couple of hacking manuals in there.

http://www.undergroundnews.com/files/texts/best.htm

Zone-h has some really good txt files and tutorials on computer security located here:

http://www.zone-h.com/en/download

Packet-Storm also has tons of txts files you can learn from

http://packetstormsecurity.nl/

If your looking for a specific tool, just search it in Google.

This site has some OK tools

http://www.astalavista.com/

Just use google = ) Those links should help you get started