[liorean]

Hmm, sounds like an interesting challenge - I'll throw together my own version:

Number.prototype.ordinal=function(){
    var
        nModTen = this % 10;
    return (this + ['th','st','nd','rd'][nModTen > 3 ?
        0 :
        ( this % 100 - nModTen != 10) * nModTen]);
}