Join Date: Mar 2005
Location: Kitchener, Ontario
Bikes: Rebel Cycles Trike, Trek 7500FX
It depends on the size of the TV. There's no way you'll be able to generate enough power for a 42" plasma display, but you could run a 20" LCD with ease.
Now, as for how to rig up those rollers... You'll probably start with a 12V DC motor, hooked up to a capacitor bank and a voltage regulator. That might be able to power the TV if it is 12V compatible (ie portable camping TVs), otherwise you'll need an AC inverter as well.
The motor will need to spin at a certain rpm to generate 12V, so make sure that for a set cadence (ie. 80rpm), the motor is geared to spin at the optimum speed.