Hi Kevin!
As Louigi has correctly stated, we can't best advise you without knowing exactly what it is you want to do.
There are a few software repositories for the Mac such as MacPorts and fink etc that specialise in porting (mainly) Linux software to the Mac to save you the effort. This includes graphical Linux apps too because Apple have an X server for OSX but such apps aren't as well integrated with OSX as native OSX apps so you're recommended to run the native ports where possible, if they exist.
I'm no Apple dev and have only briefly played with Xcode but my general impression is that non-graphical, terminal only based Linux software should be easier to get compiled and running under OSX than anything that needs X11 etc. It depends on their dependencies.