Having idle time while at work, commuting, at home or in a queue? Here's a real time saver. Practise your GMAT in that few minutes (or hours). GMAT Club introduced GMAT Toolkit app for iPhone, iPod and iPad (HD version)
Summary of app: (extracted from iTune website)
The most powerful preparation tools from GMAT Club:
✓ the high quality questions with explanations from top tier testprep companies: Knewton, Manhattan GMAT, Princeton Review and Manhattan Review.
✓ Build your own 2500+ questions set
✓ Keep grader/error/time log for Official GMAC books
✓ Always study in timed mode with the GMAT timer
✓ Learn idioms on the go
✓ Stay motivated with inspiring quotes from GMAT Club members
The latest version (updated 25 Feb 2012) is priced at US$24.99 and available here.