An interesting site collecting and displaying flight plans is up and runningm the site OpenFlights is a site for “flight logging, mapping, stats and sharing”. They have also decided to release their data under the Open Database License (ODbL):
One of OpenFlights‘ most popular features is our dynamic airport and airline route mapping, and today, we’re proud to release the underlying data in an easy-to-use form, up to date for October 2009. Behold 56749 routes between 3310 airports on 669 airlines spanning the globe.
The data can be downloaded from our Data page and is free to use under the Open Database License.