System	Directory for finding applications	1 or 2-click application installation	Automatic updates
iPhone	App Store	"Buy Now"	iTunes/App Store
Ubuntu	Synaptic/Software Centre	apt-url	apt
OS X	MacUpdate/iUseThis	Download an internet-enabled disk image, move the app to /Applications.	AppFresh/Sparkle
Windows	Web	Download an installer, run it.	Application-specific