How can someone advertise for a site with 3,000+ visitors per day without using Google AdSense?

Chitika (http://chitika.com/) is definitely worth looking at as a backup to Adsense. The ads are targeted based on the search keywords that a user used to get to your site, so it works well if you've got lots of traffic coming in from search engines. And you can run both Chitika and Adsense ads on the same page, which might be a good way to test the viability of Chitika ahead of time. If you get most of your traffic from Google (and most good Adsense site do), getting a Google penalty (having your site removed from the index or demoted in the search results) is a bigger risk than having your Adsense account disabled. Because without traffic, not even Chitika can save you.

I truly do like Google - but I had heard the horror stories, and now I've seen one first hand for a client of ours.  After one month, we received a notice saying we were guilty of click fraud, and they shut it off.  We appealed on behalf of the client, and they still banned them from adsense.  All of the money they were entitled was taken (or rather, not distributed to them), and no explanation was given other than they might be click frauding people.  The website is a reputable business, with an online history over 10 years long and never so much as a complaint from advertisers.  The down-side is not the money that was lost, it is the not knowing why they've been black-listed, plus, not having that inventory back for their other paying advertisers who could have used it. So that being said - until Google becomes more transparent, I haven't been able to recommend them to any of our clients.  We do a lot of business with them on the AdWords side, and I was actually one of their Beta testers before AdWords - so I like Google as a whole - but there's something not right with AdSense. Although I don't have much to any experience with the following, these are other networks that have been recommended to me when I've shared our clients story: OpenX Marchex/Industry Brains Pulse360 AOL Advertising/Quigo Kontera InfoLinks Vibrant Media Good luck!

There are various platforms available that can earn you good income like chitika, infolinks, kontera, etc. (Usually they don't recommend using them with another similar ad network as you can see in the comments by their official reps at: http://nabtron.com/using-kontera-and-infolinks-together-on-same-site-page-at-same-time/ )  However, I would recommend you use only adsense and start your own website ads as alternate and also start having your own products to sell.