One emacs function I have been using more frequently recently is webjump. It allows you to easily perform web searches from within emacs - While I use firefox instead of an emacs-based browser, it still saves valuable time instead of first switching to the browser. You can customize the sites you can search by customizing the variable webjump-sites. However, while Webjump is useful for less-frequently searched sites, for ones that I perform searches for on a regular basis I have functions such as the following:
(defun google (query) "googles a query" (interactive "sQuery:") (browse-url (concat "http://www.google.com/search?q=" query)))
This allows me to bind keys to search specific sites, such as C-M-g for the above-defined google query.