image  Mailplane 3

Mailplane is the best way to use Gmail on your Mac.
More ...


image  Spootnik

Spootnik connects OmniFocus and Basecamp by synchronizing their data back and forth. You neither have to have MobileMe nor to install anything on your Mac. It just happens.
More ...


image  Backboard

Backboard is a MacOS application which gives a dashboard-like overview over task, reminders and calendar events of Backpack, a product of 37signals. It's available for free.
More ...