Wherever you go in the world on your gap year, my advice would be to not just flit from place to place but to stay in the places you enjoy the most for as long as you can to really get a sense of the people and place - you'll appreciate it way more. You can do this by finding a job in the local community that can fund your stay and future travels. If you speak English, then teaching is the obvious option, or work on a farm or whatever you like (see organizations like WWOOF, or meet locals by coach surfing). Also, take one set of smart clothes for when you're away, you never know what you might be invited to (I was invited to a wedding in India by the headmaster at the school I was working in). Finally, avoid the agencies if you can, organizing it independently is cheaper and gives far more options and freedom.
WWOOF: www.wwoof.org/
CoachSurfing: www.couchsurfing.org/
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