I worked at a video store for a year and a half and seen a fair amount of cinematic drivel during my tenure there.
Notable examples would The 6th Day, Domestic Disturbance, Blair Witch 2: Book Of Shadows, S1MONE, Big Momma's House, Family Man, Ballistic: Ecks Vs Sever, What Women Want, Inbetweeners, Battlefield Earth, Gone In 60 SeconRAB, The Next Best Thing, Hide And Seek, Planet Of The Apes(the Tim Burton remake), Cast Away, Rock Star, Driven, the Psycho remake with Vince Vaughn as Norman Bates, Paycheck and Snake Eyes are the ones that spring to mind immediately.
I would probably put a lot of films with Eddie Murphy, Robin Williams and Robert De Niro(well most films he has made in the last 10 years) in the category of worst films ever made too.