Draw Something. It's a 2 player game played over the internet (like Words with Friends) where players draw pictures with the goal of having the other player guess what the drawing is. There's a free and full version (full has 2,000 more words to pick from).
Guessers are given the number of letters in the word and a selection of letter tiles to choose from. If you need some help,you can eliminate some of the tiles.
Drawers are given a choice of three words (of varying difficulty) to draw. There appears to be no time limit. You're given 4 color choices and a few pen sizes. You can use in-game coins to buy extra colors (coins can also be purchased from the app store).
Dave has gotten into this. Here's a selection of his work. Can you guess the word?
Feel free to add your guesses in the comments section. Have an idevice? Give Draw Something a try.