Chances are, if you’ve every had a boring, monotonous, soul-killing job (and who hasn’t?), then you’ve likely taken a few moments out of your uneventful day to jump onto an online gaming site and jump into a quick round of Zuma or golf. Now Yahoo, one of the largest providers of free casual games, is looking to make a bit more income by introducing new ad-supported games.

Yahoo has made agreements with PopCap, Big Fish, and I-Play (as well as others) to provide 400 games by the end of 2008, all of which will be supported by pre-roll, mid-roll, and post-roll ads. There is no word yet how many of these games will be new and how many are re-releases of titles already on the market, but when it comes to casual browser games, it’s usually more profitable to bank on familiarity over innovation anyway.

According to Kyle Laughlin, head of Yahoo Games, "In-game advertising is a win-win for Yahoo Games, our partners and our users. Yahoo Games will safely and simply monetize our games experience while providing the best and most popular games free to market enthusiasts."

The company hasn’t mentioned what specific ads will be shown, but since their stated goal is to reach out to the female 35 to 54 demographic, you can assume there will be lots of female-centric products. Of course, they could throw us a curveball and advertise for nothing but Harley Davidson and Skoal tobacco, but I think that might miss their target group by just a smidge.