Chrome’s custom search engines are incredibly useful, though they come with one minor annoyance. If you want information about a service, Chrome assumes you want to search that site:
I use Chrome’s custom search engines as a way to get stuff intuitively. For example, when I type amazon, it gets ready to search amazon.com. But that sucks when I want some juicy tech news about Amazon (like the latest on their new Seattle grocery delivery service). If you search Amazon for “totes” or “fresh”, you won’t find that news. So I just put a forward slash before I type Amazon fresh in my omnibar, and the custom search engine never catches on. Google doesn’t complain, and gives me exactly the result I want.
Another way to work around this would be to avoid giving services keywords that are the same as their name (such as az instead of amazon, which has the advantage of being shorter), though if you like to keep your keywords longer and easier to remember, this is an easy way to get around Chrome’s custom search engines when you need to.