Working copy backup using diff/patch files.
Add a "Backup working changes" button to the AnkhSVN toolbar. Configure the backup location in Tools > Options -> Source Control. Include tags in the path which can be replaced with the Solution name. This will allow developers to easily backup their current work without checking it into subversion. Having your working copy backed up to a network share, would be useful for day-to-day work that doesn't warrant its own feature branch.
An option to automatically backup at regular intervals would minimize lost work in the event of a machine failure.
This could possibly be scripted using the command line, but I see this being a very useful feature by having it built-in and on the toolbar.
Currently a patch file can’t express all information in a working copy. A new feature partly available in subversions trunk should make it possible to fully capture all changes (including copying and renaming files) in the new svnpatch format.
A full implementation of this feature will probably require Subversion api changes that are scheduled for 1.7 or 1.8.