[XStab] is just a system used in servers to keep stats and other cool things. I only know of one server that has it. It is called "The Ganja Palace".
[XStab] works by giving each player a profile. It can be veiwed by typing !whoami, !whois Sabres, etc. In the profile is the players stats, trophies, feats, credits, etc.
Credits are earned by doing certain things and just by playing well. Credits are like money and can be used to buy things such as ammo or guns. Since there is only one life per round, a player can use !newlife to respawn for 1,000 credits. Credits can also be gambled. Type "!challenge <players name> <amount>" to challenge any player to battle. The first player to kill the other wins the battle and the credits.
Also in [XStab] you get ranks. Level 3 medic, Level 5 soldier, etc. To achieve these ranks, the console tells you what to do. For example: "To move up to Medic Level 3, you need 50 more revives!"
To recieve a trophy, you must get 20 ammo given in one round, 15 health given in one round, 5 revives, etc. Since the rounds are so short, this is hard to do. Also in [XStab], teams only win by killing all of the other team, objectives are turned off.
Thats about all I can think of about [XStab] for now. IMO, 24/7 Beach should use it.
P.S. Don't make fun of me for going "overboard" with this post, I had time on my hands.

:)