Kevin Kelly has posted a piece on his Technium blog about four modes of no-baggage travel:
1) Total Nada
2) Just Pockets
3) Day Baggers
4) Minimalist Borrowers
Total Nada. In this mode you take your passport, a toothbrush, some cash, a cell phone, the clothes you are wearing, and that's it. It's pretty radical. You have to be in a certain zen state to enjoy this, but like many things, once you jump in it is not hard to do. This mode is great if you are drifting, going with the flow, and not trying to do anything else. If your travel entails producing something, you'll need tools (keyboard, or cameras, or books, or maps, or hand tools), which takes you out of this mode.
But a number of folks sail off this way every year. For one example, Jonathan Yevin travelled for a month in Latin America in Total Nada mode. He wrote of his adventures in Budget Travel. (That's him [above] with all his luggage.):
I just completed a month-long, bag-free trip through Central America. I ran the full length with nothing but the clothes I was wearing: cargo pants, maroon T-shirt, and gray fleece tied at the waist. On my person was an American passport, a Visa credit card, about $50, a toothbrush, a tiny Canon digital camera with extra battery, a Ziploc bag of vitamins, and a copy of The Kite Runner, whose chapters I tore off as I read them. Begging for toothpaste, it turns out, is a great way to make new friends.
...My lack of luggage did raise suspicions, among travelers and government officials alike. Border crossings were particularly interesting. Unsurprisingly, immigration agents were annoyed, as they clearly missed the opportunity to rummage through my bags in search of weapons or smuggled Rambo bubble gum. What about washing clothes? An amused agent asked, "vas a recorrer mi tierra desnudo?" ("You gonna run around my country naked?") A valid point.
...I would recommend a second pair of socks; you can streamline by putting one in each pocket. Sweaty T-shirts and boxer briefs doubling as swim trunks can be dried in transit by hanging them from a car window (assuming the vehicle has windows).
Body odor notwithstanding, I was free to walk anywhere at any time and to completely improvise and revise my itinerary in liberating fits of spontaneity. All of which brought me into more intimate interaction with the people and places I came to visit.