I recently got an e-mail about this one. It's a little bigger than the smallest permanent based Tumbleweed; but smaller than the largest, and real stairs to the bedroom, not a ladder. It calls for a crawl space; but looking at the study plans, I don't see why it couldn't be adapted to a slab or, depending on your location, even a full basement. It actually looks big enough to use real kitchen appliances (no dishwasher).
http://www.dailygazette.com/news/2008/feb/17/0217_cottage/
I downloaded the study plans for it from...
http://www.sheldondesigns.com
The above link is on that page as well.
The 5 plan bundle for it is on special through Jan1, 2009 for $99. I may call it an early birthday present and order a set for myself (after I get done modeling it in sketchup). I can visualize things better in 3-D than I can from paper plans.