During my ongoing search for creativity boosters, I found Sketchcrawl.com:
Sketchcrawl.com. is the brainchild of cartoon artist Enrico Casarosa, who after a night participating in a pub-crawl for a friend's bachelor party, where a group stops in at multiple bars on a given route and has a drink in each, came up with the idea of a sketch-crawl. Armed with some pencils and watercolors, Casarosa spent an entire day walking through the city, stopping to sketch whatever interesting came into view.
"Giving yourself this kind of mandate for a full day changes the way you look around you. It makes you stop and see things just a tad longer, just a bit deeper ... needless to say I loved it," writes Casarosa on the website.
How about taking a "writing crawl"? Spend an entire day, walking wherever inspires you, and stop every once in awhile to write.
This can be done alone or with friends. If you take the walk with friends, I suggest swapping notebooks along the way and writing in each other's a time or two; it will commemorate the walk and who was on it, and your writing will be a gift for your friends that they'll have in their notebooks forever. (Notebooks do last a long time these days...)