Got a bike? Get one of these:
http://www.bicyclebuys.com/Items01.a...fo&SKU=0100190
You clamp your back wheel's axle into the frame, and you have an indoor exercise bike for a lot less than the price of an indoor exercise bike.
You'll want to get a smooth tire for your back wheel - knobby tires make a helluva lot of racket.
I have one, set up in front of an LCD TV with DVD player. I watch movies and get my exercise, and no one can see me
(that's not why I have it - I got it so I could keep riding when it snows. I'm not one of those crazies who tries to bike on ice)
There are three types of bike trainers. No-resistance (useless because you quickly get the wheel spinning faster than you're pedaling), magnetic resistance (that's what I linked to), and fluid resistance. Fluid is the nicest, and the quietest, but they do have a bad habit of leaking, and whatever that crap is that they put in there will ruin anything carpet. . .I go magnetic -the noise isn't any worse than a regular exercise bike with a fan-wheel, and they don't wear out like the fluid ones do. The resistance increases with your speed and basically keeps a little something for you to work against so your legs aren't spinning wildly.