- Currency Conversion
- Reiseplanung Routenplaner
- the absolutely great great circle mapper and information on american airports
- Flight tracking sites (mainly for the US):
- Flytecomm Flighttracker (nice maps, but requires constant reloads)
- aeroseek (realtime tracker with not so nice, but more informative, maps but no reloads)
- galileo booking system to check fare class availability
- Airliners.Net
- Airlines:
- Delta Air Lines and the somewhat geeky Flyertalk Delta Forum
