just some runner wrote:
I would also recommend buying an expensive bike and get into cycling. I recently got hooked due to a running injury and have really grown to love cycling.
I think the key here is to buy something high end and get your money's worth (use it!). If you buy an entry level bike you can get a workout but you aren't going to be able to keep up with other fit guys until/unless you develop some serious fitness yourself. Spend $1500 - $3000 on a carbon fiber bike with good components and if you live in a cold area, buy a Kinetic Road Machine or CycleOps trainer so you can get some fitness going indoors. Seriously, you will be amazed at how hard you can work and recover so quickly with no impact exercise.
http://www.bikeforums.netis a good resource to find out more
You have to admit that is a really shitty option when you could spent $120 on shoes, $45 on shorts, $20 on a shirt $12 on socks and be good to go.