I work for a medium-sized company (around 600 employees) where we have never had any formal Change Management.

We have, however, put in a system for automatically recording code changes after the event, so we can roll back if (or when!) things go wrong.

I also created a Change Log database a couple of years back. It seems as if I'm the only one who uses this with any consistency, but I like having a record of what I've done. It saves time whenever I think "I'm sure I've done something like this before", and I like the idea of having something to point to if someone says "Just what have you been doing lately?"