Word Driven from Headlight Software, Inc. transforms a cherished car trip game into a fun iPhone application. You're given three letters to work with (in the real world, you'd get those letters from passing license plates, but here they are automatically generated by the application) and must produce a word using each letter in the proper sequence.
The underlying dictionary seems pretty robust, handling nearly all the words I threw at it. At each possible completion, the application chimes to let you know you can submit the word as-is. If your word continues on further, you can keep typing, otherwise you can tap to submit.
The application offers both a timed challenge mode and a "complete n words" mode, allowing you to pick whether you want to race the clock or simply work your way through a standard number of puzzles. While the game itself is free and ad-supported, in-app purchases ($0.99 each) allow you to expand the game for additional difficulty settings.
I found the game easy to use but I took exception to some of the GUI choices, especially the hard-to-use custom keyboard and the off-center text entry for top winners. The application could use an interface spruce-up but even as-is it's a fun way to while away some time.
Word Driven has been submitted to Apple for approval. When it goes live, it should be available at this URL.