To add on to Kelly's post, I am including alternative sort parameters which can be used to sort on additional fields.
sortfield=numviews&sortorder=asc (sort lowest # of views > highest # of views)
sortfield=numviews&sortorder=desc (sort highest # of views > lowest # of views)
sortfield=modified&sortorder=asc (sort newest > oldest)
sortfield=modified&sortorder=desc (sort oldest > newest)
sortfield=owner&sortorder=asc (sort owner name A > Z)
sortfield=owner&sortorder=desc (sort owner name Z > A)
sortfield=avgrating&sortorder=asc (sort low rating > high rating)
sortfield=avgrating&sortorder=desc (sort high rating > low rating)
Cheers,
Eric
Esri Tech Support