Google Chris Evans sings, and you'll pull up some vids from Not Another Teen Movie. I don't think I can link it because OMG there's some vulgar language and BEWBZ!! But he's actually got a really nice (untrained) voice!
Here also sang in What's Your Number (another reason why that horrible movie works for me on a lot of levels)
Honestly, he sounds really, really good in NATM though. I just can't post the vid here
Also, this is as good as time as any to post this gem: