I subscribe to the Word of the Day from this site. I don't often learn brand new words, but I enjoy hearing about related words in English, how the word evolved to its current meaning, or even tips on how to remember to spell them.

I saw this, specifically designed for English learners, and thought I'd share.

http://www.visualthesaurus.com/cm/worksheets/2526 / -- This one is on idioms.
The problem is that Visual Thesaurus requires a paid membership, doesn't it?
The thesaurus does, but the articles are free - or they should be. If the link doesn't work for anyone, I'll delete the thread.