Use the awesome Airline route mapper software:

http://arm.64hosts.com/

detailed in this thread:
http://www.flyertalk.com/forum/trave...ows-based.html

In the view menu go to options and set a maximum distance you're looking to fly...maybe 3,000 miles? Click your home airport and see all the routes that qualify. Can also view by single airline or alliances.

or at the least go to:

http://www.airlineroutemaps.com/