Most any savvy computer user is probably pretty handy with a free compression and archiving tool (like, say, 7-Zip), but not everyone they send files to will be. The Confessions of a Freeware Junkie blog points out that IExpress.exe, a built-in utility you simply type into the "Run" menu in Windows XP or "Start Search" in Vista, can create self-extracting archives to be emailed to anyone using Windows. Just choose "Extract files only" while clicking through the wizard interface, choose the files to be zipped up, and the end user only has to double-click to get them. IExpress also works as an easy way to convert batch files into executables. Need more info on IExpress? Check out Microsoft's help page on the tool.
Did you know? Windows has a built-in tool to create self-extracting archives via 'Iexpress.exe' [Confessions of a Freeware Junkie]