As a programmer I am used to dealing with diff files. If you do not know what a diff file is, here you can find a nice description.
They are simply text files so they can be viewed with less, more, cat and other common utilities. The main problem is that those utilities do not recognize these files' special syntax.
cdiff (/usr/ports/textproc/cdiff) is a small utility that shows diff files in a colored fashion. It can be used this way:
$ cdiff file.diff
Of course, Vim can be useful here too ;)
svn diff | vim -R -