Like Google Talk, you can consider placing your favorite Google services like Gmail, Google Reader, Google Calendar, etc. in the Firefox sidebar so that content is always accessible without you having to switch any tabs in Firefox.
Figure 1: Gmail Inbox placed inside Firefox Sidebar
Here are some popular Google websites & tools that can added to the Firefox Sidebar. Thanks Steve for the idea.
Google Gmail - http://m.gmail.com - With Gmail running in the sidebar, you can compose new emails, browse your Google contacts or get notified of new emails in Gmail.
Google Notebook - http://www.google.com/notebook/m – The mobile version of Google Notebook lets you browse existing notes or add new notes from the Firefox Sidebar.
If you want to do more, add the desktop version of Google Notebook to Firefox Sidebar using this address - http://www.google.com/notebook/ig?hl=__MSG_locale__
Google News - http://www.google.com/m/news – This is the regular Google News homepage with stories from all categories. If you like to see only technology related news in the Firefox Sidebar, use http://www.google.com/m/news?topic=t
Google Docs – http://docs.google.com/m – With the mobile version of Google Docs, you can browse existing documents but can’t create new stuff.
You may however use Google Docs shortcuts to quickly create new documents, spreadsheets or presentations from Firefox Sidebar.
If you are just looking to browse documents, also try the following URL as it gives you an option to instantly search Google Docs documents. http://docs.google.com/API/IGoogle?up_numDocuments=100&browserok=true
Google Calendar - http://www.google.com/calendar/m – Keep track of upcoming events and appointments by placing Google Calendar in the Firefox sidebar. You also get the option to add new events to your Google Calendar.
Google Reader – http://www.google.com/reader/i – This is also for the iPhone but you can use it it catch up with you favorite RSS feeds while surfing the web in Firefox.
Google Photos - http://picasaweb.google.com/m/ – This lets you browse Picasa Web Album photos in the Firefox sidebar. You may also put comments on Photos.
Related: How to access websites using email