You need to first install FxFactory, then you can go ahead and install the free AE plug-ins one by one.
The free plugins for AE listed below are just a small selection of the ones available. The complete list of free AE plugins can be found here.
Yanobox Barcode generator creates animations that are European Article Numbers aka EAN-13 barcodes.
Star Titler allows you to easily recreate the look of the opening titles made famous by the original Star Wars movie in 1977.
The Coverflow style scrolling image generator plugin for Adobe After Effects. The plugin also works in FCP and Motion.
Five free plugins for AE, FCP and Motion: MultiSpace, iSight Live!, Rack Focus, Opposites and World.
Two free plug-ins for After Effects, FCP and Motion ColorChannel and EdgeSharpen.