I'll admit - one of my favorite iPhone games ever is iAssociate 2 from TicBits. Imagine, then, my delight when I found out that the developer had launched the game on Facebook. For those unfamiliar with the iPhone game, iAssociate 2 is a word association game that is very simple in concept, but easily addictive.
Each level is comprised of a web of words. You'll be given one or perhaps two words to start (based on the web's design), and you'll be able to see all of the words directly related to your starting word via word bubbles. Of course, you'll have to come up with this associated words yourself, but you will be given the number of letters that the word contains.
Your starting level, for instance, gives you the word "Breakfast." From there, you'll need to think of all of the things associated with breakfast (toast, eggs, cereal, and so on) and enter those into the game to see if they match. Once you find a word, more branches stem off of it, until the entire web is one grand and complex setup, filling the screen.