Have just come back from a week in Italy, where I taught conversational English to native Italian speakers. I only found out about this recently and applied on a whim last-minute, but I'm sooo glad I did it. Met some incredible people, stayed in a really nice location and had lovely food - definitely made a few friends for life :)
I'm quite shy and have pretty crap self-confidence and self-esteem. I had no idea what to expect from the week, and it definitely made me come out of my comfort zone a few times. It's now given me a travel bug, and I've signed up for a similar course in Germany. Part of me feels quite chuffed that I did it :)