List of sites that could join

This is a list of all sites that need user registration and use a database.
All of them could join your site.

Antica http://antica.bestweb.net/
Arcanum http://arcanum.fxfi.net/
Binari0s http://www.binari0s1.com.ar/ Spanish
Black Zero http://www.black-zero.com/
Sered http://www.cyberarmy.net/sered/
Daedlaus http://www.daedlaus.com/sk00l/
Enigmagroup http://www.enigmagroup.org/
Hackerss http://www.hackerss.com/ Spanish
H4ckThis-P4ssB0x http://www.h4ckthis-p4ssb0x.de.vu/ German
Mod-X http://www.mod-x.co.uk/
Mr01001101 http://www.mr01001101.co.uk/
Noxistes http://www.noxistes.org/
OverTheWire http://www.overthewire.org/wargames/
Project Euler http://projecteuler.net/
QuitBoss http://www.quitoboss.fr/
Quizzers.info http://challenge.quizzers.info/
SERS http://sers.student.utwente.nl/
W3Challs http://www.w3challs.com/
Zero Identity http://www.zeroidentity.org/