If you drop a couple large for a Computrainer, you can ride virtual courses or even race friends and strangers via the internet.
If your budget isn't that large, pick up some videos of LeTour or other bike races. Universal Sports broadcasts a lot of bike racing. I've got a drawer full of tapes and DVD's I've recorded over the years. I recall one Paris-Roubaix from a few years ago where the camera guy gave us an angle on the leader that felt like you were riding right on his tail. Spectacular.
That said, I mostly play video games (NCAA football.....), or watch NFL and NASCAR. If you want a real killer workout, ride an NFL game, but turn up the resistance and sprint through all the commercial breaks.