For the most part, Raspberry Pi users have only had one or two really strong operating systems to work with. If you're looking to try something different, Pidora is an OS built on the Linux system Fedora.
Pidora is slightly different than something like Rasbian in a few ways. It comes with a handful of different software than Raspbian, including lots of text editors and programming languages. You also get a "headless mode" to operate your Pi without a monitor attached (and with the clever feature to say your IP address out loud when speakers are attached).
As you'd expect, you can also download a lot of additional software from the Fedora repository. Pidora has a slightly different look and feel than Raspbian, but it's worth checking out if you're looking to try out a new OS on your Raspberry Pi. You'll find everything you need over on the Pidora page.