i have to admit that if i could buy one as big as the table then i would do. a bigger mouse that requires both hands to move it would be cool too - or maybe just a mouse that is so big it fills the space of the new mat and makes everything seem normal again.
on a serious note, i bought the mat with the intention of cutting it up and only using a third of it - that is the area i'm actually using for the mouse right now (the rest being under the keyboard). i've a 24" monitor and i have the mouse speed set quite low - this is to make my movements more precise with graphic editing software. hence a large mat allows me to make large sweeping movements if i need to - so i get the best of both worlds - precision without sacrificing large movements.
i've also used padding under the keyboard for several years. when this extends forward to the front of the desk it makes things really comfy for resting your wrists on. maybe i'm just fragile but i notice that my wrists ache after long periods of lying on a hard table top. so, this super large mouse mat now doubles up as wrist mat also - and nothing slides about which is handy.
(secondary purpose will help when playing shootemup games - or so i'm lead to believe.)