When we talk about mobile search engines, there are really only two names in the conversation: Google and Bing. But did you know there are quite a few other options, and you probably already have them available on your phone?
Many apps offer built-in search engines, and they may be able to direct good amounts of traffic to your site, depending on your market. For example, YouTube is actually the second most popular search engine being used. Yes, YouTube gets used for searching more than Bing.
Sherwood Stranieri analyzed these in-app search engines, and has a helpful breakdown of what less recognized mobile search engines are best for your industry.