OS X's built in application launcher is clean and simple and tends to get overlooked.
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Built-in to OS X.
Pro Can add application collections
Pro Design, fade-in animation effect
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Con All apps are automatically included, even uninstallers
Con Limited configurability
You can customize a keyboard shortcut to Launchpad but that's about it.
Con Organize and ordering applications is a nightmare
App organisation in Launchpad is the same as the iPad. You can only move one app at a time, if you drop an app on a full page, it will offset all the icons on the pages to the right. As the total of apps could be very important, as all bundles are automatically added by the app, you have to drag each app icon, one after the other, and scroll through the pages, to put it in the wanted location. The difference with the iPad, is that on the iPad this can be done with iTunes.