1 of my more successful markets has been the corner betting market in football, mainly the English Premier league and the Champions league. It's a market that escapes most punters but you could say the same about odds compilers, such is the potential of the possible ROI% and the generous odds/lines often given by the sportsbooks.
If you fancy taking on the corner betting markets, I'd recommend a Bet365 account. They cover all games in the English Premier League as well as European football.
Some punters that do dabble in the corner betting markets like to back the unders but it's backing the overs and corners handicaps that I myself specialise in. I find the lines/handicaps are often wrong the prices often generous, more so than in your regular markets.
Variables which influence corner count
Here are some of the factors which are generally overlooked when it comes to corner betting but when taken into account give you a significant edge over the bookmakers/other punters/layers:
Pitch dimension: My studies over the years have shown(which stand to reason) that pitches with the smallest surface area tend to clock up the most corners. Short and wide pitches are the target for high corner counts.
Manager style of play: How do the teams approach the games? Do they play a short passing game or a more direct game involving getting the ball into the box as often as they can? Do they focus attacks down the flanks?
Widemen/attackers/fullbacks: The key to winning corners is getting in behind the defense. Pacey forwards, wingers and attacking overlapping fullbacks are key to doing this. The more they are present in a team, the better.
Game pattern: Is it likely to be a cagey cat and mouse game or a fast end to end game? Generally games between the 'big 4' in England will have a low (under 11) corner count because of the chess like and slow game pattern whereas open end to end games will have a lot of box action and space in behind leading to high corner counts
For each game I take all these factors and more into account in regards to corner betting as well as using recorded corner stats (for, against, total, home and away) for each team and then I create my own line and price. After that, go hunting for something more generous, hence offering me value.
You'd be surprised how often you'll get it right if you take these factors(and more) into account.