We never used anything on our cats as they never went outside.  But when we took in a tiny kitten last fall she was infested big time and the other 3 cats soon were as well.  Our vet suggested Frontline Plus so we ordered some of that and have been using it since October.  It seems like it's working quite well.  She also gave all cats a single does of some sort of oral medication but i don't recall its name.