Andre and the Config Database worst case scenario
Andre has posted an article on how to re-create the SharePoint configuration database. This really is a "solution of last resort", that is, something you can try if all else fails (in fact I would only do it after you have finished panicking).
With that said, it's nice to have a document to follow, that has been tried and tested, if you do ever find yourself in that situation.
The final interesting thing to say here is that it can be done relatively "safely", that is, it can be done without losing any critical data (ie. Team Sites or Portal Content). You will lose some things however, from memory your managed paths and proxy settings at least will be lost (will find out what else...), but these should be easily reconfigured. If you ever find your self in a "disaster recovery" situation (naturally caused by some sort of hardware fault <grin>), where you need to bring your environment up on a new and separate farm, then you are also in a situation where you need to recreate you configuration database. You should not restore the one from the previous environment because the new farm is different to the old one.