Welcome to Mac-Forums, quattro4life! I take it that you are not a new Mac user?
Any app you used on your older Mac will do for the most part. If you want the apps to run natively on Intel, look for software that has the "Universal" or "Universal Binary" tag or mention on the webpage. Just make sure your Mac and OS version meet software requirements and you should be fine.
If you listen to a lot of music in iTunes, I would suggest You Control: Tunes. It puts a Previous, Play/Pause, Next, and song selector dropdown menu in your upper menu bar. It's a nice feature so you don't have to keep going back and forth between iTunes and another app. That one's probably my favorite so far.
Even though it is a Linux oriented guide, the list of "Must Have" apps is completely general, specific only to the Mac itself. There is also a good section called "The Care and Feeding of Your New Mac", all about routine maintenance.