I noticed that the tourCMS.com website had a rather smashing search feature on it; after looking at the code it looks like it is powered by Google Personal Site Search but as there are no ads showing I was wondering is this the business version or is it in fact not a Google powered search at all?
It seems the logical choice as we all tend to be quite mindful of how our sites appear in Google's results already these days :) We query Google and then process their XML response using PHP, you are correct we pay a small annual fee to get access to the results via XML and remove any Google branding (pricing on the above link).
Another option I've looked at in the past is Yahoo BOSS which is free however (I believe) you need to pass your users clicks via Yahoo and potentially display sponsored links whch were both dealbreakers for us. Picosearch is also worth a look.
Another tip: If you are using Google Analytics take some time to configure the "Site search" tracking functionality with Google Analytics (you don't need to be using Google Search engine) you can then over time start building up a picture of trends regarding where your users are getting stuck or perhaps what they are looking for that isn't being found / doesn't exist.
Sorry to drag up an old thread; Is there an existing compiler for taking the search results (as objects) and converting it to XML or is this a script that you wrote inhouse?