I don't know if this falls strictly into this field, but on an aesthetic note, I'm very happy with Unsanity's Shapeshifter.
I have gotten tired of the brushed metal appearance of most the of applications in OSX, but thanks to Shapeshifter, I can give my whole desktop and the apps nearly any appearance and theme I choose, thus making my iBook just a bit more unique for me.
I used a previously hacked version for a while, but guilt got the better of me, and I finally paid in and now use Shapeshifter guilt-free.
I have gotten tired of the brushed metal appearance of most the of applications in OSX, but thanks to Shapeshifter, I can give my whole desktop and the apps nearly any appearance and theme I choose, thus making my iBook just a bit more unique for me.
I used a previously hacked version for a while, but guilt got the better of me, and I finally paid in and now use Shapeshifter guilt-free.