If you have compelling content that will keep people on each page for awhile, consider rotating your display ads. Your developer should be able to write a simple code that allows the ads to appear on your page for a certain period of time (say, 30 seconds), and then rotate out to be replaced with new ads.
When you do the math, you can understand why this can be such a profitable undertaking. Let's say you have three display ads on your page, and you're selling them for 50¢ CPM (cost per thousand) each. In other words, you'll get 50¢ for every thousand ads you show in each of the ad areas on your page. In this example, you have three ad placements, so you've monetized your page at $1.50 per thousand ads. But let's say your visitors stay about 45 seconds, on average. If you're rotating your ads at a rate of 30 seconds, then each site visitor will actually see six ads on each page instead of just three. This will increase the page value from $1.50 to $3.00—a big difference!
Rotating your ads, though, can be a little addicting, and you may feel tempted to decrease the rotation time in order to increase revenue. Resist the temptation! Thirty seconds should be the absolute fastest that ads should rotate, and even that might be a little too quick. Ad rotation should also be used only as you're getting your site up to speed or in short-term situations, when you may need to increase revenues to meet a certain goal. But don't base your business model on it. Viewers may find it distracting, and most ad networks won't like it. In fact, if you rotate too quickly (I've known people who have tried to game the system by rotating ads every 10 seconds, which is just ridiculous), they may pull their ads from your site and decide not to pay you for whatever ads you did show. Ideally, if you're going to rotate your ads, start at 30 seconds and wean off of it by increasing the rotation by 15 seconds every month or so until you're not rotating anymore.