If you are not using 7-zip, you need to install it.  It will unzip just about anything, including install shield files, msi files, gzip files, tar files, rpm, deb, iso – over 20 different kinds of files.  It will create compatible compressed files, but it also has it’s own 7z format that has a higher compression ratio that zip.  It will make encrypted files and self-extracting executables with better encryption that regular zip.  Of course it’s open source, mostly LGPL.

Example:  The other day I needed to install a printer driver on a machine that a customer connects to with remote desktop.  HP had the humongous 205 MB download with all the utilities, but all I needed was the driver, so I downloaded the huge basic driver package, which was only 61 MB.  It was an executable, so I tried running it and it complained that the USB was not working while looking for the printer.  This was a virtual machine and I didn’t need USB.  I tried renaming the file to .zip and unzipping it using the Vista built in feature, but it could not read it.  So I installed 7-zip and was able to extract all the files and just install the driver. One more happy customer.