I haven't jailbroken my iPhone yet, but SBSettings has a solution for autorotation, and brightness, and almost anything that annoys me with my iPhone on a daily basis. Now that I have seen SBSettings, I am considering jailbreaking. Apple should do something like SBSettings. http://theappleblog.com/2009/06/22/sbsettings-why-i-still-ja...
You're right, it's almost enough to push one into jailbreaking. But I think I'd prefer to run a supported configuration. Computers shouldn't be unnecessarily exciting.
I buy most of my software in the Appstore but I've also paid for software on Cydia.
Lookup SBSettings (has a button for quickly toggling WiFi on and off, awesome for battery life and my initial reason to jailbreak), RotationInhibitor, Lock Calendar and iDitDahText (brilliant!).