From this post on the venerable Joel on Software:

Go to walkscore.com, and type in your address. What you’ll get is a score with detailed locations of common destinations within walking distance.

My work got a 66. Where I went to college got a 72.

And my current residence gets a 75.

Walkability is one of the things that influenced us when we bought our home and why we like living in this area so much.