md5deep and hashdeep - Cross platform recursive hashing and auditing programs, respectively. Computes MD5, SHA-1, SHA-256, Tiger and Whirlpool hashes. Can also match against sets of known hashes. The latter program uses multihashing to conduct a computer forensics audit.
FRED - The First Responder's Evidence Disk
Miss Identify - Program to identify Win32 executables that don't have an executable extension. Can also identify all executables.