I have an iPhone app and have about 3000-6000 users a day. I currently use mobclix and http://i.imgur.com/GzkDf.png is a summary of what returns I'm getting from advertising in my app.
Are there any ways to get a better return? Less than a dollar a day seems low to me, but I've never really put ads into anything yet, so maybe that's just normal for that amount of users.