Tom Reestman has a nice post showing differences between the Remote application, for controlling iTunes from an iPhone, and the built-in iPod application (via John Gruber). I agree that Remote is much nicer, although it’s missing a few features. It would be nice if iTunes’ unzoomed controller could show the cover art and controls like that.
I don’t like the data detectors that Apple added to Mail in Leopard, because I never use them and they interfere with selecting text. I just figured out that you can disable them by entering defaults write com.apple.mail DisableDataDetectors YES in Terminal. Normally this type of hidden preference would be easy to look up in Google, but I only found a bunch of ideas that didn’t work, and as of this writing there are zero hits for “DisableDataDetectors”.
Update (2013-04-16): Alas, this no longer works in Mountain Lion.