Right now it's just one because the site is in Beta, but when it launches it'll have a dark theme to go along with the default. After that I plan on releasing a lot more. The best thing about this, is the Homepage of the site takes on the skins design too. 🙂
On old forums I had I used to allow members to choose from, 4+ styles. However, I've learned that it's best to stick with just one style. Makes modding the style more easy, and then you can develop advertising banners, affiliates, and all that from just ONE style instead of 4.