Have you ever wanted to find out what speed/duplex your network card negotiated to? mii-tool is the tool for you.

List NIC speed and configuration: mii-tool
eth0: negotiated 100baseTx-FD flow-control, link ok
Verbose mode: mii-tool -v
eth0: negotiated 100baseTx-FD flow-control, link ok
product info: Intel 82555 rev 4
basic mode:   autonegotiation enabled
basic status: autonegotiation complete, link ok
capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
advertising:  100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control

Check out YoLinux Tutorial – Linux Networking for more great tools.