United Airlines Timetable mashup - Here is someone who has taken United's airline timetable and has done some simple routemapping with it. Specify a starting point (for example YYZ for Toronto, Canada), and it lists all possible destinations from that point. You can also map between two points. I see an IncidentLog-style mashup with all airlines on the horizon..
ChicagoCrime.org now plots "Crimes along a route" - Google Maps mashup pioneer Adrian Holovaty has tipped me off about a new feature he has added to his Chicago Crime tracker. It's called "Crimes along a route", and allows you to draw a line along a route and plot the crimes which have taken place along this path. His site notes the potential benefit: "It's useful if, say, you walk down a certain set of streets each evening, you take a certain bus route, or your kids take a certain path to school." His blog contains more information. Head over to this mashup to give it a try..
Hamming it up on Google Maps - Here's a mashup of amateur radio licenses in the U.S. (a.k.a. "hams"). You can search for a ham by callsign, or search by state or zip to find hams in a desired locale.