Firefox: If you use a lot of Google services, chances are you have a lot of them bookmarked. If you'd prefer quick access through your bookmarks bar, Google Shortcuts is an extension that adds them to your URL bar.
After you install Google Shortcuts you can pop into the add-ons page and disable any services you don't use. Then, head into the customise window (right-click by a new tab), and start dragging whatever services you want to the right of the URL bar. It's simple, but it gives you quick access to the services you want without cluttering up any menus.