Craftsman has a torque wrench that goes from 20 to 250 inch-lb in 3/8" drive. About $70 or so at K-Mart.

The Allen bits that I have for it are also Craftsman, and are ok except that they're chamfered slightly (which makes it easier to get them engaged properly in the bolt) but which removes some mating space once you have it in there. This isn't so good on bikes since a lot of the bolt heads aren't that deep, and the torque wrench is fairly large and unwieldy itself - you have to use care to keep the tool from popping off the fastener. So I'm keeping my eyes open for some that are more squared off and with a lower profile overall.

The technique Hillrider mentioned above is pretty clever and intriguing to me and I think I might give it a shot. Sooner or later everyone gets some worn out allen wrenches and sockets, and this would be a way of turning two bits of trash into something useful.