Guess what we are using to manage Wrike product development efforts? You're right - Wrike.
I personally have used Wrike to manage my personal tasks as well as to share other tasks since its first prototype. By using Wrike I have gradually been able to build my personal hierarchy.
About a month ago we hit a major milestone - Wrike became the primary project management tool and bug tracking software for our own company. We are still in beta and working hard to polish everything, but the product is already a pleasure to use.
Right now under the "Wrike Development" folder with tasks, we have three separate subfolders: "Wrike To Do" (where we store our plan for developing new features), "Wrike Suggestions" (where we store different ideas for product improvement from ourselves and our users) and "Wrike bugs" (software terrarium). Those folders in their turn have subfolders like "P1", "P2", ... in "Wrike Bugs" ("P" stands for priority).