Is there any reason jQuery doesn't include methods for getting the .first() and .last() items in the current collection? I frequently use the :first and :last CSS selectors, so a method equivalent would be useful (and intuitive: I just had someone ask about a bug in their jQuery code caused by their assumption that .first() was a valid method).

Implementation:

jQuery.fn.first = function() { return this.eq(0) };
jQuery.fn.last = function() { return this.eq(this.size() - 1) };