your group at a game can do anything they can all agree on. you can have a forced call or raise,even a insurance type fee to fold like half the bet or bigger antes, or more blinds, a small blind on the button is not uncommon, you can do whatever condition you want. Expermint with different things for your game. another interesting variant to betting is buying a card on the river. typically in stud and draw games, you set a price to buy a card on the river, maybe something like the price of a big blind or something that is based on the pot size. there are no federal laws that restrict this, so use your imagination. For my dime I think the best way to increase the action is to add an ante.
this is a list of things I have seen over the years to sweeten a pot,
Allow any player to straddle from any spot.
in lo-ball games they used to have a voluntary kill, where a player after recieving thier in some variations after receiving their first card cards could post a live kill before the draw, works just like any kill giving the player whom made the kill, last option to raise.
a Kill with a condition defined where the player has to post a live blind, typically after winning a pot that exceeded a certain size or has won two pots in a row.
More live blinds, three blinds under the gun, or a blind on the button.
anted, even a small ante goes a long way toward much bigger pots.
forced raise, saw this mostly in razz games, after the bring in all other players are required to raise or fold.
buying a card after the river, when a player can buy one more card, the proceeds which go into the pot, this is best suited in games where a player hold all thier own card, but with a little imagination, can be modified to suite community card games.
adding wild cards to the game.
double flops, have two flops, makes for a lot of action. one can vary this between playng for a split betwenn the hands fo the best hand of each flop, or best hand takes all.
a five hole card varation of omaha, where the best five card hand, in a players hand gets the half the pot.