I've blogged before about RedGate and their SQL tools and I've just tried SQLDoc. Once again I'm amazed; another cracking tool. Once installed, it had documented 7 largish databases within a minute, producing complete documentation for them as a set of formatted HTML folders and files. It documents all of the metadata as well as giving you a SQL script so the item can be recreated. I can now check these into source code control, or more immediately, keep them so I can rollback some changes to a known stable version of the database without worrying about losing the test changes.
I really don't know how I managed without these tools for so long; SQLDoc is just one of them, the others I've used provide schema and data comparison between databases. They are all easy to use, are designed well, and actually work the way you expect (a feature lacking in so much software these days). Given the current exchange rate, there's never been a better time to get them. You won't regret it.