The Tower by American Airlines
I'm an aviation buff, so maybe that colors my opinion, but I love this app. I hope they add more functionality to it in future iterations, but for now I just like the way it looks sitting there on my monitor. The Tower lets you check the status of flights, find out where a flight in the air is at the moment, and get the weather and gate postings for AA hub airports.
Debra Littlejohn Shinder, MCSE, MVP is a technology consultant, trainer, and writer who has authored a number of books on computer operating systems, networking, and security. Deb is a tech editor, developmental editor, and contributor to over 20 additional books on subjects such as the Windows 2000 and Windows 2003 MCSE exams, CompTIA Security+ exam, and TruSecure's ICSA certification.