So you’ve checked Ubuntu Software Centre and scoured the Synaptic Package Manager. You’ve even googled for the application you need and come upon an obscure developers website with a tar.gz file and instructions to configure; make; make install.
Well if you’re new to Ubuntu Linux and still shy of the command line, check out getdeb.net for a broader list of applications and games that you won’t always find in the repositories. A .deb file is the Debian Linux (Debian is the distro Ubuntu is based on) version of .exe or .msi for Windows. It’s pretty much a one or two click process to get hold of some excellent software that for some reason doesn’t make Ubuntu’s repositories.