Biter Links
Every vampire has a biter link (at the very least potentially). Raven's website, for its own protection, has an anti-spam policy that goes like so: You are not allowed to post your biter links in places you do not control - on a forum, in a chat room, in communities. Therefore, you can post them on places you do control - your personal homepage, a forum you run, chat rooms that you own, Quizilla quizzes, your Yahoo! or AIM profiles, et cetera.
The structure of biter links simple: http://quiz.ravenblack.net/blood.pl?biter=[vampire%20name]. The only exception to this is if you have a space in your name, in which case the biter link can be accessed in two ways - either using the space, or replacing the space with a plus sign, like: http://quiz.ravenblack.net/blood.pl?biter=[vampire+name]
Example: Mictian, were his biter link not disabled, would have his at http://quiz.ravenblack.net/blood.pl?biter=Mictian
The biter links themselves are useless to gain bloodpoints. However, if the person who clicked on the biter link then signs up for the game, you are given 10 bloodpoints for the 'achievement' and are one childer richer. Great places to gain bloodpoints with the biterlink method were, for example, popular Quizilla quizzes - Mooncalf was immortal this way, having had, for a significant amount of time, a constant source of blood so powerful that his bloodpoints were going up while he was being scrolled - a sorry sight indeed for all who wished to oppose him.
It should be noted that Raven added the ability to turn off one's biter link to guard from people getting into trouble with communities that ban such things as 'quizzing' (having your biter link posted on Quizilla or another excessively high-traffic site) while a malicious user did just that 'on behalf of' the biter link owner, thus promptly getting them exiled. You can change this setting on your 'My Vampire' page.
Of course, if you're generally opposed to getting bloodpoints by having your biter link posted or your clan disallows biter link usage (e.g. the Splinters of Dusk, or other self-immolating philosophy clans), then that's a nice option outright.