Treno
http://www.psc.edu/networking/treno_info.html
Treno tells you what a good TCP should be able to achieve (Bulk Transfer Capacity)
Easy 10 second test, no server required
damp-mhpcc% treno damp-pmrf
MTU=8166 MTU=4352 MTU=2002 MTU=1492 ..........
Replies were from damp-pmrf [198.97.151.50]
Average rate: 63470.5 kbp/s (55241 pkts in + 87 lost = 0.16%) in 10.03 s
Equilibrium rate: 63851.9 kbp/s (54475 pkts in + 86 lost = 0.16%) in 9.828 s
Path properties: min RTT was 8.77 ms, path MTU was 1440 bytes
XXX Calibration checks are still under construction, use -v