Assembla.com are now going to charge for SVN hosting*. You can host open-source projects, but for most of us that is not an option.
I have migrated to
http://www.xp-dev.com. It's quite new (and hence looks very basic at the moment) and it's free. There is an import/export option coming, but in the meantime, it was imported for me, just by sending my Assembla export by email. The site says it will stay free forever, with alternative ways to fund the site.
So far, it's all been good. Once they imported my site, I used "Relocate" in TortoiseSVN, and just carried on as normal.
*
SVN is a source-code management system that allows you to roll back to previous versions, branch, tag and work on source code as a team, or from multiple locations. It can be controlled entirely through Windows Explorer using TortoiseSVN