If you installed Firefox 1.5 beta 1 you probably found that many of your extensions quit working. While some of them are indeed incompatible with the new Firefox, most of them just need a little prodding. Nightly Tester Tools is an extension for Firefox that does a lot of stuff mostly useful to people who use—as the name implies—nightly builds, but it also includes a feature that's very useful for the rest of us: It lets you force Firefox to believe any extension is compatible with whatever version you're running, and lets you install "incompatible" extensions, too.

Like I said, some extensions really are incompatible with 1.5b and will mess things up, so obviously use Nightly Tester Tools at your own risk. If you're using the beta, though, you're probably already used to living on the edge.