OneLook Dictionary Search is a cool service that able you to search a list of related words or phrases from a word and concept:
OneLook’s reverse dictionary lets you describe a concept and get back a list of words and phrases related to that concept. Your description can be a few words, a sentence, a question, or even just a single word. Just type it into the box above and hit the “Find words” button. (Keep it short to get the best results.) In most cases you’ll get back a list of related terms with the best matches shown first.
One of the useful way of using it is getting word based on some clues. For example: enter s?nt?:christmas will give you the word santa. It is an ultimate cheat tool for your crossword puzzle.
OneLook Dictionary Search – [OneLook]