$20 Hydration pack from the Army Surplus store. Comparable in size to the M.U.L.E, and not even half the price. It came already with the bite valve cover, and insulated tube sleeve. Another 4 buck and I got a smoke grenede pouch, in matching camo, that i use on the shoulder strap for housing my cell phone.
Beats putting a regular bottle in the outside pocket of my Timbuk2 when riding my 07 Schwinn Madison.