I'm not sure if the 8th (or 10th as it was played at the Open) at Royal Liverpool counts. It's not a short par 4 to me, but the Open field played it as a short 2-shotter and it provided much fun. The 13th and 16th at Lytham are both good short two-shotters. The 282-yard 14th at Ganton (not an Open course, but it's held just about everything else) is a great short par 4 and I love the 3rd as well. Also among the championship courses which have not held the Open, the 8th at Nairn is a little brute. The 6th at Hunstanton is a corker, again not an Open venue.