if you ever need to compare files in two directories to look for what data is different between one and the other.
I used it to help Pendleton trim down a 185mb hotfix to a 15mb update with just the files that have changed specifically since their last HF was applied.
T:DATATechcoltFile Comparison Utilitytcm801x32.exe
Use with caution, of course.
In answerbook.