Zimbra Desktop was one of the first applications to embrace Web 2.0 and show us what it could offer. It's been a little left behind by todays generation of 2.0 apps but is still an interesting option.
Zimbra Desktop is an AJAX-based collaboration tool that aims to ensure that you can work on and offline. For example, using Zimbra, you can write emails, add new appointments and edit documents offline and when and when you reconnect, changes will be automatically synced to the Zimbra Server.
Firstly, installation of Zimbra Desktop is lengthy, requiring you to sign up for a Zimbra account so make sure you have a bit of time spare before starting on this. You have to configure all of your server and mail details in your Zimbra account before you can start working. Zimbra Desktop syncs Yahoo! Mail and Gmail accounts and it can read email from any POP or IMAP email account, including AOL, Hotmail or business email. The developer touts Zimbra as a possible replacement for Outlook for Windows users, although I'm not sure if Apple Mail users would really consider switching. Syncing with Zimbra Desktop is fairly fast although even this could be a made a little quicker.
Zimbra Desktop elements in Zimbra Desktop such as inbox, contacts, calendar or documents appear in a new tab in your default browser. You can search items very quickly using the search field at the top of the interface although again, this can be a little slow. It has to be said that the overall interface isn't exactly slick and could do with being given a much nicer OS X look or Cocoa revamp.
If you regularly work offline, then Zimbra Desktop could be worth a try for you. However, it is blighted by a rather lengthy installation process and slowness in certain departments.