Recently I’ve been playing around with a couple of tools which can extract files from downloadable install packages, such as those created with NSIS, InstallShield, Windows Installer or NSIS. The tools are Universal Extractor, which supports most install packages (with the exception of NSIS) and 7-Zip, which as well as being quite a good general-purpose zip utility will also open NSIS packages, plus some Windows Installer and InstallShield packages – note that you’ll need the latest beta version to enable some of the functionality.
Why would you want to do this? Sometimes installers don’t work for no apparent reason, so you can extract the files and install the program manually yourself. Or you may have a copy of a program that you don’t need, but would like to install the fonts that it ships with – you could extract the fonts from the installer package and install them manually without installing the whole thing.
Mac users needn’t feel left out – if you download a program which has an installer package (as opposed to just an application in a disk image), you can right-click the package and choose ‘Show Contents’. You don’t need to install any extra software, though Pacifist is a shareware tool that adds many extra options.