Cafe Race have come up with a water bladder system that is worn like a bike messenger bag. This might seem a little weird, but it works great. Even with 64oz of water slung against your lower left abdomen, you barely notice that you are wearing this sling. The drinking tube follows the sling up and over your right shoulder and is held by plastic D-rings near your right collar bone. To drink, you simply reach up with your left hand and guide the tube under your helmet.
The adjustable sling is constructed of Cordura nylon and includes six Velcro closure pockets to hold your wallet, cell phone, keys, garage door opener, condoms and dew rag. One of the pockets is constructed entirely of nylon mesh, presumably for carrying wet items or drying jerky. The pockets are great for small maps, 3x5 notepads, wallets and other fairly wide and flat stuff. However, the pockets don't have full width Velcro, so I really wouldn't recommend carrying keys or change in them. The cell phone pocket is sized to fit most cell phones and has a flap closure which held my phone securely, while allowing easy access for gloved fingers.
In use, the system is unobtrusive and the bite valve works great (much better than the valve on a Camelbak) with good flow, and no drips. It is also easy to get on and off, over bulky jackets and helmets, making it more likely to be used than similar gear which can be a PITA to wear.