Craig offers a very good advice (as usual)
And as other users said before me, it really looks professional and well built
Also, if your main purpose is to sign people up (at least for now) I`d suggest to enlarge that option
It can be passed over easily by users, especially since it`s on the top of the screen and visitors have to scroll down to the useful content.
Make sure the visitor is well informed of whats waiting for him/her when they register, and make sure that the information is very easily accessible (e.g. in a viewable box on the homepage, so they see it without having to click anywhere)
A strong point though, the lovely moving flash on your homepage has no link, it`s definitely something people will click, and you should direct it to a page that will make them want to signup
I like the site, and I wish you the best of luck