Here's a great story from the Seattle Post-Intelligencer about a mobile cat adoption center:

All day Tuesday, Henry DelleChiae had been keeping a secret from his girlfriend.And he'd been telling lies.
He had asked Laurie Conklin to meet him for lunch in Fremont, after a meeting there. There was no meeting, but there was a pug-nosed yellow school bus parked on 36th Street, which Conklin cluelessly walked by twice after DelleChiae guided her there.What she didn't know was that they'd come to the bus for a very special Christmas present: a cat.
The little bus could have been named the Meow Mobile or the Cat Car, but the Northwest's first mobile adoption center is called Whiskers on Wheels (WOW). Run by the non-profit, all-volunteer folks at Whisker City, an overspill shelter for cats, WOW has been causing spontaneous eruptions of smiles and good cheer wherever it goes.
The bus, which has room for 22 kitties, is outfitted with three-story cages lined with cushy fleece rugs, litterboxes, food, water and ample toys. Its narrow aisle makes it difficult for two people to pass at once. Purchased for $1,000, the former Yelm school district bus gets six miles to the gallon. It costs about $5,200 to run it for a month.
WOW's goal is to raise $10,000 and find good homes for 30 cats in its first campaign, Dec. 4 through January 2. So far, about $3,000 has come into the coffers and 20 cats have traded their mobile home for a terrestrial one.
"We've had nothing but positive response," says April Brown, founder of WOW and Whisker City. "And the cats love the bus. They just love it."
WOW parks in front of welcoming businesses, such as pet stores and veterinary clinics.