I've posted this before, and hopefully someone at Wizards has the same ideas.
They are working on monster builders, and should expand the Encounter Builder tool to use it. They should not only continue this work, but allow me to save my creations to the database. Then allow other subscribers to not only see my monsters, but those that others have created.
Once this is done, they need some good mapping tools. Not some big complicated never going to happen 3D virtual world, but a simple drag-n-drop tile maker. Let me use them to plan out what I'm going to do with the D&D tiles, or simply print them. Let me save and share these as well.
At some point, work in a tool for Skill Challenges. Incorporate all the errata and advice, and again let me save and share these.
Finally, we'll be at the end game - the Adventure Creator. I create the combat encounters, skill challenges, and maps into a whole adventure. Let me save this and upload it as well. Before long you'd have the biggest seller for DDI you could imagine - an online repository of user-created adventures. Don't be a jerk, and allow unofficial fan conversions of classic adventures as well as original creations. In no time flat you would have thousands of adventures free for the taking for any DDI subscriber. Have a rating system and Editor's Choice each month to highlight the really good ones.
If I were them, that is what I would be working towards.