Old Crow Medicine Show is an interesting concept and a killer live show to say the least. As described by some as alternative bluegrass, they consist of 5 guys plucking various string instruments and singing folksy songs. The only atypical thing I can think of that qualifies them for alternative bluegrass vs plain ole vanilla bluegrass would be their age. They are relatively young and would look more like Good Charlotte than a bluegrass band.
Regardless their show was awesome and they have a new album dropping this week, so be sure to check it out.