37signals have announced their latest project Backpack (which was codenamed Honey). Since it hasn’t launched yet, details are thin. But I believe that this will fit nicely in between their current offerings: the free Ta-da List and their popular Basecamp project management tool.
DHH states that
Backpack helps you bring life’s loose ends together
DHH also mentions in that same post that Backpack was the reason for adding the ability to receive (as well as send) email to the ActionMailer portion of Rails.
So I’m guessing it’s a psuedo-project management tool for the home user. Useful for tracking tasks and their associated people, actions, etc. Basically, the ultimate personal information manager (PIM) to help you gather your email, contacts, schedules, notes, documents and more in one central location. We’ll just have to wait the month-or-so until it officially launches to find out for certain.