I ran into a situation where the order of registration of the areas in my ASP.NET MVC application was important. So far, I've been using AreaRegistration.RegisterAllAreas() to have all areas registered automatically. Sometimes I got lucky and the areas were registered in the order I wanted, but sometimes they weren't, leading to mysterious 404 errors. It took me some time to diagnose that the problem was indeed the ordering, then some more to find the right google query. http://stackoverflow.com/questions/1639971/mvc-2-arearegistration-routes-order describes my order, and Eilion's answer saved my day: a way to manually register areas in any order I choose:
var area1reg = new Area1AreaRegistration();
var area1context = new AreaRegistrationContext(area1reg.AreaName, RouteTable.Routes);
area1reg.RegisterArea(area1context);