Actually, if I really wanted to disapper, I'd cash out the entirety of my bank account and get a plane ticket to somewhere like Australia (I wouldn't fly to my final destination because plane tickets are far too simple to track). I'd make my way up to Southeast Asia via short range boats with local fisherman (paying cash). In Southeast Asia, I'd keep going the boat route up the rivers through Vietnam and Thailand, then overland through Burma, up through India into Nepal. At this point, I might stay put, though I might try to cross the Himalayas and get into Tibet. Now are we talking no contact at all with anyone, or just staying hidden? No contact at all with anyone means you have to find a place which is both remote and hard to access, but also has an ample food supply, which doesn't describe very many places on Earth.
Alternately, I'd drive down Central America, making my way via a series of cars, taxis and possibly travel in boats across the Caribbean, down to South America. I'd go through South America until I hit the Amazon rainforest, and set up a camp for myself deep enough in the jungle that no one would stumble upon me by accident.