AddressBookSync helps to get your contacts organized. This Mac OS X application transfers Facebook profile pictures and birthday information to your Mac OS X Address book and iCal ( there's one for Outlook users, too). If your mobile phone supports synchronization with Address Book, when acontact calls, the person's picture will appear. Similarly, contacts' birthdays will synch with your iCal, keeping you updated when you're not logged in to Facebook, too.
The Facebook Toolbar for Firefox is an extension that alerts you to new friend requests, messages and event invitations, so you need visit the site directly only when necessary. The tool bar also lets you set your status and share content directly to your page without leaving the webpage you're currently viewing.
Read more about web 2.0 in CIO's Web 2.0 Drilldown.