PC Hardware Tests
Beep Codes - Power On Self Test Beep Codes for AMI and Phoenix BIOS
CableModem.net - Online cable modem speed test
How to Test your Modem/Phone Line
Jesse's PC Checkup - Four Great Benchmark Tests
PcPitStop.com - Lots of different tests.
Shields Up - Good tests and offers free firewall.
Speedguide - The site focuses on system performance, with areas including Broadband Internet connections, Windows, Overclocking...
