I like the idea of custom departure (or arrival) procedures.  That should be relatively easy thing.
Brian: In my case, this would require planning a route with everything that's involved there, writing down that route, going back and loading the DP and then re-entering the route.  I frequently need to do significant route planning for the survey work we do.  This means loading a start and end point, then all the stops in between, re-ordering them based upon a number of factors, wash rinse repeat.  It certainly can be done as you suggest, it's just not the easiest (I could also save/load my final route and then manualy insert the 3 or 4 departure waypoints).
This certainly is *not* a high priority request.  Just thought I'd throw out the idea if it was easy.