Is it possible to block News Feeds generated when friends use certain applications?

yep. go to your settings (top right) > application settings I think. Its changed a bit by the looks of things, but I turned all of mine off some time ago.

I’ve been wondering this too, my feed keeps getting flooded by the latest fad application…also what happened to the ability to get less/more info about a person in your feed? All I can do now is ignore them or have everything they do.