Helpful Tool: WinMerge

Need a tool that can do a diff of those really long reports you just generated? Have two script files that look like they contain the exact same info, but they're behaving differently? You need a diff tool. From their site:

"WinMerge is an Open Source differencing and merging tool for Windows. WinMerge can compare both folders and files, presenting differences in a visual text format that is easy to understand and handle"

WinMerge is Windows only, so sound off in the comments if you have a favorite diff tool for OS X or Linux.

You can download WinMerge from here.