just a good mic, and a good recorder, everyone you ask will be biased toward different equipment, but i think the main thing to do is just experiment, find a mic that sounds good with the singers voice (it seems like most people cant go wrong with a sm 58 but i just bought an sm 57 used and it sounds great.)
p.s. from watching a dashboard confessional live performance chris was singing through an sm 58, , , but, the biggest factor would probably be the singers skill,.. i personally like dashboard confessional but i dont think chris has a very good voice, but it works great for the songs he writes.