Search alternate sites from the Omnibox
This tip isn't exactly a secret, but it's just too useful to leave out. Anyone who uses Chrome knows that the Omnibox doubles as a search box. You set your primary search engine (Google by default) by right-clicking the Omnibox, selecting "Edit search engines," choosing a site from the list and clicking Make Default. But you can also use a nifty shortcut to do a quick search using any search engine you've previously used in Chrome.
Type the first letter or letters of the site's URL, such as "y" or "ya" for Yahoo, then press the Tab key. A Search site button like the one shown below appears. Type in your search query to search using that search engine.
There's a small gotcha to keep in mind with this trick: If you haven't already visited the Web site and done a search, the Search site button won't appear. But it should work for any site at which you've previously searched, as long as the site adheres to the OpenSearch standard.
To tell whether a site adheres to the standard, visit the site and do a search, then right-click the Omnibox and select Edit Search Engines. If the site you're on appears in the list in the Search Engines dialog, it does follow the OpenSearch standard. Only the search engines that appear in this list will be able to use the Tab key trick.
Get more tips
If you're looking for even more Chrome secrets, you'll find a few in my blog post "Three hidden Chrome features you'll love." My in-depth review of Chrome covers other tips, such as how to make Web applications run like desktop applications.