Homeless for a year (at least): living in 12 countries for one month each, staying mostly at places found on airbnb.com. (Staying in each place for one month each.)
Currently in Amsterdam at this place: http://www.airbnb.com/rooms/23023
Sitting on that red couch writing all day. Everything I own in one suitcase upstairs. (Except my bike, outside.)
I love it. Thanks airbnb. :-)
Interestingly, there are a lot of things out there that don't seem negotiable at first, but you would be surprised how open a lot of people and businesses are to the idea. You just have to try.
It's not just about the money though. There are disadvantages in signing up a "guest" for a month. What if they are really obnoxious? Three or four days you can wait them out, but a month?
I would guess that people who stay for long stretches like that tend to look for full apartment listing, since the host might also be obnoxious, and it might get old to stay with someone for a month even if they're just neutral.
Feel free to make fun of me in a year when it turns out completely different than planned. :-)