According to one embodiment, an arm support device includes a sack of flexible and stretchable material. The sack is open at one end and closed (or closeable) on all other sides. The user inserts both arms into the sack and pulls the sack over the upper arms and shoulders. With the arms thus inserted, the user is free to relax and allow the stretch of the sack to provide arm support. In some embodiments, the sack has no other openings besides the top end, and in these embodiments the arm support device doubles as a travel bag for carrying small items.