Absolutely. There are "number of post"-dependent groups like God member and then there are non-post dependent groups like Founder of Hocomania. (Sorry folks, that group is full up!).
We can add as many groups as we like from what I can tell. Come up with what you want and it should be easy to implement. As long as the Boss doesn't mind, of course.
[edit] We should do 750 too since tmeri and ataloss just crossed that line.[/edit]