If you have a bike then you are probably already enjoying taking it out for long rides on the weekend. We tend to stick to the same route and it can get a little boring. The problem is that you don't want to end up 20 miles from your home only to realize that you've got to ride 20 miles back.
Bicycling.com has thousands of routes that will solve the problem. All you have to do is enter your location and it will bring up a list of possible routes for you to chose from, complete with distance, elevation, and calories burned if you maintain a certain speed. I looked it up for my town and discovered some great routes that I would have never been able to figure out on my own. I plan on trying one soon.