Sometimes you've been working all day on several different logically distinct chagnes, and you forgot to commit your code in between. Using git citool can be very helpful for breaking up your work into nice bite-sized chunks at the end of the day, even if you weren't so careful during the day while you were working.
git citool can let you select which specific hunks of a file (or which specific lines) to commit in a particular commit, so you can break up (non-overlapping) changes made to the same file into several commits.
(It seems that you use Subversion. I don't know of a tool that does this for Subversion, but you could look into using git-svn, the Subversion adapter for git, which will change your life.)