So you've gotten started with Linux, but you're looking for a new flavour besides Ubuntu to try out. Instead of installing a bunch of them from scratch, web site Virtualboxes provides a bunch of free Virtualbox images for you to test out, no installation required.
Virtualbox is a great way to try out software and operating systems without having to partition or reboot your machine, but you still have to download live CDs and go through installation procedures. Web site Virtualboxes hosts a number of Virtualbox images for a bunch of different Linux distributions and other operating systems. That way, if you're ready to move on but you aren't sure what you want to try next, you can give them a shot in Virtualbox without going through all the tedium of installation (or the annoyances that come with Live CDs).
Just head to the Virtualboxes web site, pick the distribution you want to try out, and download the image for it. Extract the archive somewhere, and then hit "Choose an Existing Hard Disk" when you create a new machine in Virtualbox. Pick the VDI file from the archive you downloaded and you'll be on your way. Hit the link below to check it out.