I wrote a Countdown letters game solver (or in fact, general anagram solver) for Android devices (download the APK file below). Source code is available on request. It's a slight improvement on my older J2ME version in that it solves as you type the letters in, and clicking on a word takes you to the definition (on a web browser).
Just download the APK file below, copy it to your device and install it. You might need to enable 'Install software from unknown sources'. It asks for the permission 'Full access to the internet' but this is just so that when you click on a word it can take you to a web browser within the application rather than loading an external browser. It is compatible with Android version 2.3.3+.
The new algorithm is much faster (was necessary to solve as you type). It creates a letter count for each word, i.e. a sequence of pairs (letter, num_appearances), and to check if a word can be made you just have to check that num_appearances for each letter is lower than the count you have for the letters typed in. It still scans through every word in the dictionary each time, but it was quick enough so I didn't optimise it further. It might be possible to get even more performance with some sort of tree structure for the dictionary.