One thing I really enjoy about the Mac development community is that there are tons of really tiny apps designed to do just one thing really well. Instead of creating some monolithic do-everything-imaginable app, try breaking it out into a few smaller apps. The Unix shell is so powerful because developers have taken this approach for a long time. You can reduce complexity drastically while allowing the user to be even more flexible with their workflow.
I just discovered I Love Stars from Potion Factory, which is a simple app for making it easy to rate your music in your iTunes library. The best way I’ve found to rate my music is to do so while it’s playing. I Love Stars makes it easy to do so without needing to remember to pull up iTunes every three and a half minutes.