TITLE: Math research in the app store
QUESTION [10 upvotes]: What apps can be found in the Apple app store, Google Play, Blackberry World etc. showcasing specific mathematics research?
(Edit - Since the first version of the question got closed, examples should showcase specific work of specific mathematicians. Tools such as Wolfram Alpha, bibliography managers, arXiv app, etc. are no longer allowed.)

REPLY [10 votes]: Akio Kawauchi, Ayaka Shimizu, and Kengo Kishimoto have created an app called Region Select, based on a knot theory paper by Shimizu. She found an algorithm to unknot a knot diagram by "region crossing change" moves, and then they realized that it was tricky and interesting enough that it was worth turning it into a game. The game got big-time press coverage in Japan. I wrote a blog post about it here. The game became popular enough that it was developed into an honest to goodness android app.
It's playable, a lot of fun, and there's a genuine theorem and research paper hiding behind it- can you figure out a strategy to win the game from any starting configuration?