My current favourites are "El Campesino", which my wife picked up in California. It's described as "La Salsa más Picante del Mundo" ( The hottest sauce in the World) and is made with Red Habaneros. 1 drop is enough for me, and I eat cayenne peppers like peanuts.
Then there's Sari´s "Hot Sauce" from Guayana. Yellow ( must be Scotch Bonnets and Mustard) with a nice flavour and good kick.
I've yet to try the "Blazing Inferno Island Pepper Sauce" from Barbados ( also in the cupboard) or the "El Yucateco" Habanero sauce. Both look suitably evil...!