Tools

md5deep and hashdeep
A set of cross platform tools to compute, compare, match, and audit cryptographic hashes. Supported algorithms are MD5, SHA-1, SHA-256, Tiger, and Whirlpool.
md5deep     Project Page     Related blog posts

ssdeep
A fuzzy hashing tool to identify similar but not identical files. In this case, 'similar' applies at the byte level. No effort is made to examine higher level structures. The package includes both a client program for matching and an API for adding fuzzy hashing to other programs.
ssdeep     Project Page     Paper     Related blog posts

Miss Identify
Identifies Win32 executables. Originally designed to detect executables that don't have an executable extension (e.g. exe, com, dll), it can also produce a list of all executables encountered.
Miss Identify     Project Page

Foremost
A linear file carver. Uses headers and footers to recover files from a data stream.
Foremost     Project Page

Volatility Plugins
Here are two plugins for the Volatility framework for memory analysis. For more, please see the Forensics Wiki list of Volatility plugins.
Find 'suspicious' processes
Find TrueCrypt passphrases
Related blog posts

Clear Memory
Attempts to push data into the paging file by allocating gobs of memory. Used to test programs to read the pagefile on Microsoft Windows.
Source Code     Win32 Executable