Affirmative is a fast SFV file verifier. It calculates the CRC32 checksum of files listed in an SFV file and compares the result with what’s stored in the SFV file. When downloading stuff from the Internet, the archives will frequently contain a .sfv file. Just run this file through Affirmative and it will alert you if any of the files are corrupt or missing.
Affirmative is free and runs on MacOS X Leopard and Snow Leopard, on both Intel and PowerPC platforms.