Highway interchanges seems like a useful one, especially since there have been multiple AARF threads on the subject.
I agree that this is the most logical 'next thing' to have a similar treatment to airports, though bejacob's point about going slow is a good one.
This one has the potential to fit better within the main TM highways code base. Without thinking too much about how hard it would be, I imagine list files entries that could be expanded to allow a list of all waypoints where the user has entered or exited a route, have this information displayed with different icons on Mapview and Showroute, and various stats and rankings could be provided.
And I agree with the overall comment that there should not be a rush to expand to all of these other ideas. An overall approach similar to what TM did in expansion to railways, where there's a common code base that ingests different sets of data, seems it would make sense.
Eh, trying to put something together like that as a .list file for all points (and not just interchanges) is more work than I'd want to do for my travels. If it were done that way I'd probably just ignore it and hope that the way it's implemented would only show up if the user engaged with it.
