As in the ones in smash where you can toggle to hide the HUD, select animations, custom backgrounds, etc. pretty much all you expect from model viewers.
And its selectable for any player you select (current class only) and for your own any class you select. Ships too!
Also! the ability to upload player models as well as Guns of Icarus to SFM. The explosion of promotional videos guys. Hell we could actually create machinimas like red vs blue but with cinematic quality!