wordoid!, by Sean Wilson, is a word game for ages 9+ that is currently free in the Amazon Android Appstore. I don't know if the price will go up later, but the reviews are very good (other than two people that could not get it to install on Android 2.2).
Game Description
If you're a word person, you'll find wordoid! to be right up your alley. This fun, fast-moving word game for your Android device is easy to learn but hard to put down.
Connect letters on a grid to create words--you'll receive new letters and earn points for every word you make. Wild card and bonus tiles add to the fun and help you boost your score. Race against the clock and see how many words you can create!
* Play this fun, fast-moving word game on your Android device
* Connect letters on a grid to create words
* Earn points and new letters with every word you create
* Race against the clock to increase your score and advance to higher levels
* Make strategic use of wild card and bonus tiles