I have been playing around with ArcGIS Online and I’m debating whether or not to implement it permanently on my site. My best guess at this point is that I won’t use it for everything I map, but it seems to have its place. I am using it right now on my new “Trailheads” page on a test basis. So far, I’m liking that it allows me to layer multiple files (I am currently using .kml files) onto a single map. It can even load .gpx files that way, so it might have a use for track display possibly in conjunction with waypoints. It can certainly handle more complex web mapping than Google Maps can.