Some casinos offer additional bets on blackjack. Often, though, they are poor-value bets.
Surrender blackjack
This gives you the opportunity to cut your losses when you have a poor hand. After your first two cards have been dealt you have the option to discontinue playing your hand and surrender half of your stake. However, if the dealer has blackjack then you lose all your stake.

Over/under 13
This is an additional bet. You can bet that your first two cards will be either over or under 13. If they score exactly 13 both bets lose. Odds of even money are paid. If you are using a system for counting tens, you can use this information to your advantage and make this additional bet when the shoe is rich in tens.

Multiple-action blackjack
In multiple-action blackjack you keep the same hand for three games and the dealer keeps the same up card throughout. A poor hand may mean three losses but a good hand may lead to three wins.