I've just heard of this today and signed up, looks interesting.
As I understand it, Quassia is free advertising for your site, and you can get this through 3 ways apparently: by writing so-called 'intel', which is some information about anything you know (e.g. about people you know, or your hobbies, or things, or whatever, just like a blog). Then by referring people, and finally by rating the intel of others. You get so called 'qassia' $, which it's like points. The more you have, the higher your rating and the more backlinks you have to your websites. It's free and really easy to set it up.
Right now it's a closed beta, remember like Google mail used to be ages ago, so you can only join by referal. If you feel like giving it a go, just click on this link
http://geltdesigns.qassia.com/
and select the big button on the left hand side of the screen 'Join'.
Oh, and do not forget to verify your email address.