Vampire was just a small server, as I said above. It had no intention of staying, as it was just a fill in server, something for us to do while we wait for them to fix some things before releasing SMP4.
Vampire had 3 (technically 4) races;
Human - Always needed. Humans played as normal, but were prone to becoming the next 3 races.
Vampire - Obvious one. Vampires could hit Humans, giving them a chance to become vampires. Vampires would be hurt in sunlight, and I believe could only eat specific things... Or maybe they didn't regenerate? I don't remember if this server was around when there was hunger or not... I dunno. Basically, you were a vampire, and you were stronger, but you had some weaknesses.
Lychin (Werewolf) - I do believe these guys came from a different mod than vampires did. They were special, and came around near end of the server, before closing down. They had a cool transformation at night, which made them faster and more powerful, they just couldn't use a weapon... I think. I wasn't around during the time, but I just know they had a different look, which was really different at the time, as I've never seen any mods that changed the player to a completely different mob at the time.
Zombie - Yes, you'd turn into a zombie. You don't play as one, though... It's basically death. Everytime you get hit by a zombie, the mob, you have a chance to be infected. If you're infected, after some time, you instantly die. I do believe there was a cure, but I forget what it was exactly... Might have been mushroom stew, but I'm just thinking of Solitude at this point.
Once again, this server was just for the hell of it at the time. I doubt they would bring it back.