Windows/Mac: Today, Opera released its own, cross-platform desktop email client. For Gmail users (and the Gmail envious), the feature set should look both familiar and welcome.
Opera Mail includes support for threaded conversations, automatic filters and labels. It also comes with a tabbed interface for managing multiple open emails or drafts. The app is handy if you don't use Gmail but want to use some of its organizational features. If you do use Gmail, your labels will be imported properly.