I've had a Manhattan but still need to try the Bronx and the Rob Roy*, a.k.a. the "Scotch Manhattan." The word left out of the recipe on MSN is, of course, vermouth.
Another cocktail that uses orange bitters is the RAC Cocktail, which someone I know first had in Paris. He liked it enough to acquire his own bottle of orange bitters. I have a bottle (rather ancient, but hanging in there) of regular bitters but if I end up liking the Rob Roy enough, I may have to add the orange variety to the liquor tray.
Here's the recipe, provided by Beefeater:
R.A.C. Cocktail (created in 1914 for the Royal Automobile Club)
40ml London dry gin
25ml Noilly Dry
25ml Noilly Rouge
dash orange bitter
Stir ingredients over ice. Strain into coupette, then garnish with a cherry and orange peel.
*although I've already had both a Roy Rogers and a Shirley Temple.