Thanks and salamat to those who replied. I may be missing it, but I don't see what I'm looking for in the suggestions. Here's a rough idea of what I hope to see:
[table][tr][td]
Application Kbps Up Kbps Down
Microsoft Update 2 64
Winamp 16 128
Folding at Home 64 4
[/table]
Bars instead of numbers would be OK. Some sort of update interval for the display is probably necessary, like update once every 30 seconds.
A lot of applications show total traffic but don't break it down by application, the way software that monitors disk i/o does. Maybe I'm the only person in the world who thinks such a display would be useful, but I can't understand why people wouldn't want to know which program(s) is/are eating up their bandwidth.