Not sure if this is a GPS or Audax topic but more likely GPS.
Strava
http://www.strava.com/ has released a route building feature. The usual clicking of waypoints and export options that you might expect, with elevation info, upload direct to device, tcx and gpx etc.
The interesting bit is that it can perform the routing based on the popularity of the road with cyclists. i.e. based on how many people have uploaded a track that contains the road.
Not that useful for local roads but could be very handy for routes you don't know that well (like on a DIY by GPS audax) - I've only played with it for a bit but the interface is ok and it seems to work well for the roads in my area. I don't really use strava for uploading info but could use it just for this tool.
Worth a look but you'll need a login