The closest thing to Kazaa is limewire, but it's not all that great.
Here are some more (with my personal opinions)
Acquisition - kinda lame and you have to pay for it now
Carracho - It's ok, it takes some getting used to
iSwipe - Haven't had any luck yet
Direct Connect - Just like the PC version
Neo - a program that lets you tap into kazaa, but it's nothing like it.
Overall the choices aren't very good, get Virtual PC and use kazaa through it.