was watching a programme on channel four a year or so back about the biggest one hit wonder singles of all time - it worked it out by the number of actual sales

thing Carl Douglas was top with Kung Fu Fighting

other high ones I remember :

Color Me Badd - Sex you up (think thats what its called)
Los Del Rio - Macarena
Jennifer Rush - Power of Love
BN Ladies - One Week
They Might Be Giants - Birdhouse in your Soul
U2 - Where The Streets Have No Name