Sparrow is a handy tool for Gmail users with multiple accounts.
The discreet interface feels a little bit like the Tweetie Twitter client with a slick Cocoa finish and an easy to scroll through threaded message window. You view previews of mails in the main window and click on them to expand the full view. You can read them in a new window or open the right pane to enjoy Sparrow's full potential.
An unread message in counter sits in your Menu Bar to keep track of mails and Growl notifications let you know when a new message has arrived. Most useful of all, you can use Sparrow with as many Gmail accounts as you want - flicking between different accounts is a synch. The only problem is that some of the functionality of Gmail is missing. For example, you can't access filtering functions and you can't edit separate signatures for different accounts.
However, most recently Sparrow has been updated to support IMAP accounts which will give it much greater appeal. Control over those accounts is limited though - you can't move mail between IMAP accounts using Sparrow for example.
If you're a Gmail user looking for a slightly different way to manage your accounts, Sparrow is worth a go.
