I chanced upon an interesting discussion in the forum page today about this new AdSense called Chitika which is supposedly on par with google AdSense. I checked out what this was all about and came up with this. Hope it answers your questions...

Chitika are another one of those networks that like Adsense pays you per click but they also offer more visitor engaging ad units. So visitors can search and compare product prices on your site.

The eMiniMalls were Chitika's first and now probably flagship product, it comes in multiple unit sizes (180×150 right up to 728×90) and gives visitors the opportunity to search and browse through a few products actually on your site (though you only get paid when they leave). You can choose relevant keywords that you want adverts to be displayed about or rely on the Chitika contextual engine to choose ads for you, both methods can be used alongside Google Adsense (this wasn't always the case but Google changed the rules recently though you should always check stuff like that your self

When it comes to integrating adverts into your site the RPU (Related Product Units) are designed to be positioned at the end of blog posts where they will display links to related products. You can use CSS to make the links and/or the list to match your sites style, even to the level of the bullets. Like with the eMiniMalls, you get paid per click. Many have mixed feelings about this format as it may annoy some visiotrs. Chitika Linx are like the content link ads offered by Kontera, where they highlight relevant words in your content and when the reader hovers over them an advert is displayed, click of said advert results in you being paid.

One of the downsides with Chitika is you don't know how much you've earned in real time. They update the stats every 24 hours but before payment they audit all clicks and remove any that they consider inappropriate (this could be fraudulent clicks or unsupported countries). and you might lose about 10% after each audit.

They reply to emails and have also been known to review sites and give optimisation tips.