When I program I often end up making 5 or 6 different versions so that way if I mess up I can return back to an older version.
In the Eclipse IDE, is there a way I can just click "create new version" or something so I don't have to make an entirely new project and copy and paste the previous source code to the new version I just made?
Is there any version manager for Eclipse? If so where can I get it?
Have you considered using a version control system, such as Subversion, Mercurial, Git, or CVS? They are designed for versioning projects without needing to make copies of them. And to be honest, they do a much better job than any individual can (when used properly) at tracking what changes were made and when.
Something that can be a little quicker to set-up, but potentially less robust to long term use, is to use a service like Dropbox, and set a Dropbox directory as your workspace (provided you aren't working on sensitive code, with personal information, assorted caveats to apply to any cloud-style service).
Dropbox does have revert options. Of course, in Eclipse you can also copy and paste whole projects.
Long-term, if you have heavy version control/group work needs, I totally agree with Thomas's solution. But, as a quick and dirty, something like Dropbox works quite well.