There are many filetypes we deal with in Windows that are compressed archives, but may not have an extension that tells Windows this. A good example would be an Android .app file. Installers are also usually just archives with some sort of script attached telling the un-archiver where to put everything. Universal Extractor, from Legroom.net is the best way to deal with these files.
You can use Universal Extractor as a full Windows application, integrated into the shell, or as a simple drag and drop app. If you choose the latter, there are also portable versions of UE out there if you want to load it up with your USB tools, or add it to a custom PE disk. A full install gives right-click options on almost any file.
I first discovered UE when I read an article somewhere on making your own portable apps. This works because UE will unpack many common installers. After unpacking, just put all of the binaries and support DLL's, etc in one directory and try to run. This method does not always work, but for many applications it does.
As a day-to-day extractor UE works fine, but I think it is a bit slow for me. Usually for routine extracting I prefer 7zip.