Anything worth bookmarking is probably worth mirroring.

Phenoelit mirror - cause they might not always be around
Unaltered Google Browser Security - Main section
Unaltered Google Browser Security - Part 1
Unaltered Google Browser Security - Part 2
Unaltered Google Browser Security - Part 3
Hex Words - List of words that can be spelled in hex
Yahoo pw_token scripts - Giant list of pw_token scripts that can be used to bruteforce un/pw combos without timeouts. This issue has been around for a good 2-3 years by now...
bios10h.go.ro mirror - Mildly interesting site
aluigi.altervista.org mirror - Game hacks and SCADA exploits. This guy must be obsessed...
Mirror of the Paypal staging server semi-hack - Just seemed like the type thing that might get taken down. Interesting web-fu...
Hauwei default passwords
Localhost.re - hosting panel/billing panel vulnerabilites
hackingteamhack.txt Hacker explains compromising hackingteam. Started with a router/vpn device. Tons of great information, especially about windows lateral exploitation.
phi-nfs-scanner.tgz NFS scanner that I wrote in bash. It works really well, just run it in a screen session on a server you don't mind getting abuse reports from. It's random number generator may need replacement.

Formerly an exploit for escaping internet kiosk restrictions. Stupid FF :-/