here's a dime, call the better index bureau

[flat labels good! folder tree good! a something about gmail (bloglines, spurl, firefox bookmarks, anything else out there to which this could even remotely apply..) , ganked from the resulting comment after someone's review of gmail got me thinking (again...omg) about all the ways having to pick - tree or list! - makes the world suck just a little bit more than it needs to.

if gmail allows multiple labels, label the message with each name you'd use in the heirarchy, then search for all those labels to get the that subset. this would work even better if the search also returned the list of all labels found in the search results so you can sort of drill down till you have the results*. if gmail added the ability to define a label's parent label, the user could opt to browse through the folder tree thus defined. i'm sure someone's already asked for it..

* del.icio.us does this. it's kinna fun spooling out declaration like what's what with what the skilled labour gets to for a living... it must get this sorta thing all the time]