we noticed some slowdowns in our internet service (hey, if you really want to Knut the Polar Bear, you should be able to). Sure enough, our 1.5M/384 service was down to this.
Download Speed: 547 kbps (68.4 KB/sec transfer rate)
Upload Speed: 211 kbps (26.4 KB/sec transfer rate)
Turns out a network card or some piece of switching gear at the CO had been set to the wrong speed. This is more like it:
Download Speed: 1318 kbps (164.8 KB/sec transfer rate)
Upload Speed: 625 kbps (78.1 KB/sec transfer rate)
The clincher was being able to show the service rep my bandwidth graphs.