I'm going to list the links I come across that I think are worthy of sharing, and don't want to forget. :)
Citation Machine- Very neat! Can help becoming familiar with writing essays much easier. I like the essay check especially!
These are such a good idea! I'm using these for my third and my 7th grader to reinforce parts of speech. I have my 7th grader use map pencils, instead of crayons. Works great! You can find a few free one's by googling "color by parts of speech."
Monster Grammar. My 7th grader likes the tests and say the explanations make more sense to him.