Digital Forensic Tools

Here is a small list of tools I have used at least once for various data analysis and carving.

Norton's Diskedit - Pretty old school but it still sometimes useful.
eRunt
BinText
PEiD
regshot
procmon
tepview
OllyDbg
import REConstructor 1.6
HxD - Hex editor that works quite well.
FTK Forenic Tool Kit, Registry Viewer & Imager
X-Ways Forenics and WinHex
Alien Registry Viewer
Advanced ZIP Password Recovery
Nessus
Process Monitor & Explorer
rawwritewin
WinMD5
Sleuthkit & Autopsy
Foremost
xxd makes hex dumps on linux/unix systems
dd (built into most linux/unix distributions)
dcfldd
VmWare Workstation or Server
Wireshark
MANDIANT Web Historian
Nessus Network Scanner
Easy Recovery Professional

Useful online tools:
http://www.virustotal.com/
http://www.cwsandbox.org/?page=home