The websites you can search using keywords and the tab key within Google Chromes address bar, the "omnibox", are found in Chrome's options window under the basic tab's search engine heading.
If you come accross a website you want to be able to search from Chrome's omnibox you must first add the websites search url string to the 'Search Engines' dialog box. This dialog screen has a long list that begins with "Default Searches" followed by lists of more websites chrome can tab to search. Open the dialox by clicking on the wrench, clicking Options and pressing the 'Manage' button.
Once you see the list, press the 'add' button to enter in an entry name, what you want to type in the omnibox before pressing tab, e.g. surfthechannel.com, and the search url which would be http://www.surfthechannel.com/search/all/1/1/%s.html. The %s must be placed wherever the search term goes. another example is http://roboputer.com/?s=%s.
Click some 'OKs' to close out the dialog windows and save your work and try tab searching your new website. When you type what was written in the keyword field while adding the site, and follow that with a tab, Google Chrome should now say "Search" before the keyword. The website should now be searchable by Google Chrome.