Tickpick is my go-to anytime I'm looking for resale tickets.
I even sold a ticket (Foo Fighters ... not Bills) once and that was also very easy! I actually sold it twice. The original buyer bought the ticket, but never completed the transfer. About an hour before the concert, I realized that I still had the ticket. When you sell a ticket, you don't get paid until the day AFTER the event takes place. I thought I was left holding the bag and miraculously, someone I was with knew someone in NYC who needed a ticket. So I sold it to HIM and transferred it to him very easily. Turns out, I STILL got paid for the first sale, so I unwittingly double-dipped.
Anyway ... I think Tickpick is great.