Vocabulary Building
I love anything that benefits a charity. In this vocabulary building website, every correct answer donates 10 grains of rice through the World Food Program to a 3rd world country. However, be aware that this vocab tool tends to target those learning English as a second language.
Just like it says. A really fast dictionary. It's kind of nice to find a dictionary without ads.
This one first asks you what grade level you are, then tests you on vocabulary according to that level. Good for identifying the meaning of words in context.
This is good for learning multiple languages. Exotic ones too!
Good for students studying for the SAT or other standardized test.