Spry Fox (they developed Triple Town) have just uploaded a new app for the Kindle. It's called Panda Poet, and they're selling it for $2.99. I haven't played it yet, so I'm going to have to go with the product listing:
With Panda Poet you use the letters on the game board to form words. Words formed from letters in open spaces create pandas. Words formed from letters near pandas make existing pandas grow.
The goal is grow the biggest panda possible. You get the highest scores from either creating the biggest possible panda or from forming the longest possible words.
To add to the challenge, each letter is only available for a fixed number of turns. Each time you enter a word, all the letters on the screen come one step closer to expiring. When a letter expires, it is replaced by a skull, which prevents you from growing your pandas in that direction. This makes playing Panda Poet a delicate balancing act: you must consider where a letter is located on the grid and how soon it will expire, not simply spell the longest word you can.