Collection of sites containing public exploits, proof of concepts and information about vulnerabilies:

Exploit DB – http://www.exploit-db.com/

CVE Details – http://www.cvedetails.com/

Packet Storm – http://www.packetstormsecurity.org/

Security Focus – http://www.securityfocus.com/bid

National Vulnerability Database – http://nvd.nist.gov/

Open Source Vulnerability Database – http://osvdb.org/

SecDocs – http://secdocs.lonerunners.net/

Secunia – http://secunia.com/