Mahalo is a search engine which is powered by human. They say that the articles listed on their search results are well organized, comprehensive and spam free. Their basic idea is to get the web pages listed on the user preferences on particular search.
They will analyze the web pages and organize them manually (I am not sure). I think this is a better way to get really valuable content. If there is no results for the search term that you have entered they will show the search results by Google,yahoo and some more on tabs, the most valuable thing is you can send them a good link for that also by just creating a free account.
Basically they will not list every page that you are sending because they have an editorial process. And they will not list the spam sites, spam blogs, phishing sites, sites that do not have original content (a copy without permission), sites that have no origin and the sites that have adult content. And on the other hand they will list the sites which have original content, consistently updated, has clean layout etc.
And also if you have site they provide facility to tell them about it. On http://www.mahalo.com/Mahalo_Publishers_Guide they give more details on that. I think it is better to tell them about your site if you have valuable and original content.
If you have any experience or more details on Mahalo please do share it with us.