The BBC website bbc.co.uk/ has a great section for ESL students. I think it could be very useful for adult classes and privates at a fairly advanced level.
Check it oot.
I would also recommend the BBC’s excellent resources for ESL teachers. In the THINK section they have articles on lots of interesting things such as the lexical approach, Dogme, blogging neurolinguistic programming, and more. There’s also a big collection of games, activities and lesson plans.