A little Google goes a long way.
http://www-rucker.army.mil/docs/usaace_info/USAACE%20Info%20Paper%20TCM-L%20Fixed%20Wing%2022%20Mar%2010.pdf
A PDF file from the Fort Rucker website. Talks about what they have. Basically, it breaks down to King Airs, Sherpas, Gulfstreams, Metroliners, and as the article points out, the C27 was planned for the Army, but it was ruled out (a damn shame). Most of those guys are either guard/reserve pilots, or on the active side, were rotary wing pilots first, and transferred in to the fixed wing side. Don't expect to walk in off the street and fly fixed wing for the Army. The only exception is the National Guard/Reserve units, which may possibly let you fight for a spot, but I'm not 100% sure on that one.
Addition: I swear I thought the Army also flew some Cessna Citations . . . someone can correct me if I'm wrong on that one.