The only product I know of that kind of fits the bill is called "Liquid Ice". It consists of a bandage soaked with a special liquid (The Liquid Ice) which works by evaporative cooling once exposed to the air, and functions just like an ice pack would (although in bandage form so it also provides compression). You can get "Recharger" bottles which is essentially a bottle full of this liquid which you can reaply to the bandage and it functions like it did when you first opened it. So a bandage and a bottle of liquid effectively functions as a reusable instant ice pack (a bottle holds enough for about 20 bandage applications and the cooling effect lasts about 2 hours).

Some links:

http://www.iomed.com/products/liquid_ice.htm

http://www.999supplies.com/product_info.php/products_id/2709

http://www.dupont.com/packaging/news/pkgnews0306.html