Diffuse is a graphical tool for comparing and merging text files. It can retrieve files for comparison from Bazaar, CVS, Darcs, Git, Mercurial, Monotone, RCS, Subversion, and SVK repositories.
An OpenOffice.org add-on which provide basic work with Subverversion. You can import/commit/checkout/update your documents into/from the repository, also with support of showing history and document diferences.