Right now, there are plenty of options from the [g] Go... shortcut, but they're fixed to specific areas of the app. None of those shortcuts today are 0,1,2,3,etc.

My proposal is making that top row of your keyboard (1,2,3...0) into shortcuts to any area of the left nav (inboxes, lists, smartlists, tags, contacts, etc.) so you could press [g][1] to get to something you use regularly within RTM.

I envision another item on the dropdown that accompanies each item on the left nav:

If unassigned: Assign Shortcut...
If assigned: Remove Shortcut [3]....

If you tried to assign a shortcut that existed, it would prompt you (you are replacing... is this ok?)