Write Rhymes is a fun little site where you can find a word to rhyme with just about any other word. I tried to use words for which I couldn’t think of obvious rhymes, but each time Write Rhymes came up with something. To use Write Rhymes simply type a word in the text box then option-click on it to see a list of rhyming words.

Applications for Education
Write Rhymes could be a fun and useful site for creative writing and poetry writing purposes (yes, I realize most poems don’t rhyme).

Here are some related resources that may be of interest to you:
Imagination Prompt Generator
Two Sources of Writing Prompts
Language Arts Links You Might Have Missed