pure web based versioning system
Get a better hosting service.  Seriously.  Even if you found something that worked in PHP/Ruby/Perl/Whatever, it would still be a sub-par solution.  It most likely wouldn't integrate with any IDE you have, and wouldn't have a good tool set available for working with it.  It would be really clunky to do correctly.
The other option is to get a free SVN host, or host SVN on your own machine, and then just push updates from your SVN host to your web site via ftp.
My hosting service does not currently run/allow svn, git, cvs on their server. I would really like to be able to 'sync' my current source on my development machine with my production server. 
I am looking for a pure php/python/ruby version control system (not just a client for a version control system) that does not require any services running on the server machine, something that could use the http interface to upload/download and sync files - basically offering a back end into my 'live' site for version control.
Additionally, I would think that such a system would be easy to develop an 'online' ide for, so that I could develop directly on the production server. (issues of testing aside of course)
Does anyone know if such a system exists?
==Edit==
Really, I want a wiki front end for a version control / development system - Basically look like a wiki and edit development files so that I could easily make and roll back changes via the web. I doubt this exists, but it would be easy to extend an existing php port of svn...