in Australia, a popular side bet on blackjack at Sydnry Star City and Melbournes Crown casino(and perhaps others) is Perfect pairs.
You can wager up to half your blackjack box bet on it. It involves the first 2 cards you get dealt being the same number ( 2 4's or 2 queens etc). A mixed pair, like clubs and diamonds, pays 5 to 1. A colored pair, like hearts and diamonds pays 10 to 1, and perfect pairs pays 30 to 1.
Sydney has just dropped the stipulation where you have to be playing the box to place a perfect pairs wager, so now you can play perfect pairs only and not blackjack. this is because it has proven to be a big money spinner for them. i suppose its good if you dont play it on everyhand and strike it lucky when you do.