md5sum is a utility used to calculate the MD5 hash of a file. Active State has made a precompiled binary available for Microsoft Windows, while most Unix-like operating systems already include the utility.
Example usage:
bash$ md5sum "A Dance with Rogues Part 1 V1.30.mod" 840df5eef81cd07e0c8967fd41514e9f A Dance with Rogues Part 1 V1.30.mod
See also sha1sum.