I've been making ringtones on my iPhone but it would seem easier on a computer. In the Mac App Store there are multiple apps that do this so I was curious if anyone had recommendations?
GarageBand.
If you're looking to turn some of your iTunes music into ringtones, you can do that for free. Here's the link on how to do that.
http://www.ehow.com/how_2160460_custom-iphone-ringtones-free.html
Audacity is what I use. Open just about any audio file, edit, apply effects (compression & EQ are the ones I use most frequently), export as m4a, then change extension to m4r.
Audacity is a free app for the Mac, also available for Windows and Linux.
EQ is equalization. In the case of ringtones I often reduce the low frequencies as they don't really come through the phone's speaker and they effect the overall average loudness...which can be increased with "compression". It takes a bit of tweaking to get the right amount of both, but when you do the ringtones can be much more audible.