Safari is by far the best browser on OS X. It's fast, has an awesome UI, and just feels better integrated in to the Mac experience.
As former die-hard firefox users, though, I couldn't live without cmd-1 through cmd-9 for switching tabs. Thanks to Safari Commander, now, I don't have to!
For 5$, one person can use Safari Commander on as many of *their* computers as they like. Two members of the same family with separate computers should purchase two copies.
WARNING: REQUIRES SAFARI 4 BETA. Available for download here. So far, I've found it very stable and worth it for this extension alone.
Buy it at the giraffesoft store!