OpenFlights
To quote the FAQ, OpenFlights "lets you map your flights around the world, search, filter and categorize them in all sorts of interesting ways, calculate statistics automatically, and share the resulting maps with friends and the world — if you want to." For example, here's my own flight map:
http://openflights.org/user/jpatokal
Which reveals that, as of today, I've flown 495008 miles (half a mil, here I come!), 179876 of which on SQ, and have spent 46.5 days of my life sitting on a plane, including going through Changi 197 times.

The whole site is free to use and open-source. Give it a spin and let me know what you think
