I use it and have for years, on a lot of sites. As with all the niches, whether you make money on it depends on the ads available in your space. For me it tends to make less money than ads. I mostly use it because it's a good reliable site search.

Note that if you have your AdSense linked to your Google Analytics, the AdSense for Search incomee won't show up in your AdSense numbers there. I dunno why, but they just don't.

Also if you use anything other than a white background, you can get some really funky looking search results and ads, so you might have to spend time with the CSS.

You can't put extra ad units on your search results page, but you can put a link unit. Or at least you could the last time I read the TOS.

And be sure to NOINDEX your search results page if you are using one on your own site. Google doesn't like search results pages in the index.

Google doesn't like search results pages in the index.

I wish that was true of certain genres.

Thank you netmeg. So how do you know how much you've earned, if the numbers do not show up in adsense account?

They show up in AdSense, they don't show up in Google Analytics.

Like netmeg I've used it for many years across many sites BUT I've earned very little from it since hardly anyone uses it. This may be because my sites are extremely well structured and easy to navigate or simply that visitors can find what they require immediately and find no necessity to use it.

Regardless of why this is so I still include it on any new site I construct since it does what it says on the tin.

You can't put extra ad units on your search results page, but you can put a link unit. Or at least you could the last time I read the TOS.

Here's a quote from the CSE TOS:

1.6 Advertising. Advertising. The Results Page or associated elements provided by Google through the Service may contain advertising, which You agree to display. The Service is compatible with, and You may apply for, the Google Adsense program (www.google.com/adsense), subject to the Adsense Terms and Conditions. If You provide Your own advertisements or third party advertisements in connection with the Results provided by the Service, You will ensure that such advertisements cannot reasonably be confused with or mistaken for those provided by Google.

Sounds to me like ads on the search results pages is OK. I may or may not have AdSense ads on my results page as part of the full site template ;-)

I run CSE, it's not a huge moneymaker, but it's worth having it there. If I have ads on the rest of the site, what's the big deal about having ads also on the search results?

Can I show ads on AdSense for search results pages in my own site?

We ask that you don't place any additional ads, including text, image or video ad units, on pages with framed search results. However, you're welcome to place a link unit or an AdSense for search box on the page.

[support.google.com...]

To my mind, it doesn't matter what the big deal is, I don't put AdSense on search result pages. They don't mention other ad networks, affiliate ads or direct ads, so those are probably okay, but not AdSense. (Also, since AdSense for Search puts on potentially as many ads as you'd see on a regular search page, why would I want to add even *more* ads to the mix? I'd rather give up a few pennies and keep the user)

Also, is there a limit on daily search queries? I have seen 100 per day on regular CSE, but can't find anything similar for adsense search engines.

100 per day is for the api, not for google cse where there is no limit.

Google CSE revenue is highly dependent on the subject matter and user intent. On the same site, which has since tailed off, I saw huge (but consistent by vertical) variances in Page RPM. Of course, that's also true of the AdSense for Content earnings.

I wouldn't expect to earn a fortune from a CSE. 150% of AdSense for Content RPM is a good indicator (for my type of site) if the search is following a page that should have given them decent ads (let's call it "dirty"). If it's a "clean" search, which has not been spoiled by previous ads, then earnings are likely to be around up to 500% the AFC RPM.

These figures come from a site that has had over 40 million visits. The site mainly got traffic from organic search, mostly Google, so "dirty" searches had already seen 2 sets of adverts (Google and the landing page) whereas "clean" searches were seeing the first set of ads.