I’ve long realized the importance of version control, but since I tend to work on most projects myself, I’ve never really been force to use one. Recently though, I’ve been working on several different website simultaneously, and I’ve found myself making changes to code on one site.
Subversion is the perfect answer to this situation. I’ve recently set up a subversion repository for my common code, and I can now work on the code on one site and ‘commit’ it. Then, just update my local copy on another site, and all of my work is merged.
Of course, I have to take care to realize what the updates will do, and that it doesn’t break functionality on each site, but the usefulness of being able to share code like this is amazing.