Diff Checker - Diff Checker is a free online diff tool that quickly and easily gives you the text differences...
DiffNow - DiffNow lets you compare text files, documents, binary files, and archives up to 1024KB in size.
Beyond Compare - Beyond Compare allows you to compare files and folders.
Juxtapose - Helps storytellers compare two pieces of similar media
Meld - What is Meld? Meld is a visual diff and merge tool targeted at developers.
WinMerge - WinMerge is an open source differencing and merging tool for Windows.