There is a good chance that I already said this before in this thread but if I did I was a long time ago so here it is and please forgive me if you read this before.
I think that WotC should adapt an app store like model, where side by side with its own products 3rd party developers could sell their products.
Couple that with digital tools that will allow the players/DMs to incorporate 3rd party developers products bellow the hood with minimal user input (you bought the book? It automatically upload the relevant stuff to your account and can be used with the character builder/monster builder/advanture builder) and IMO its a winner.
That same model would also be a platform for the every day player and DM to share and sell their own stuff, artist could sell character portraits, DMs could sell nifty advantures or even a copy of the map their players drew while exploring a dungeon (a cool handout to give other players who bought a map of the dungeon before going inside).
The store (let's call it the "Wizards Bazaar" or WB for short) should be easy to navigate with tabs for grogordnia, rule modules, settings, maps etc. With clearly marked professional and amateur content.
But more importantly, I think that it will be best to bring all the different products under the same roof, if only to make sure that every thing is at the tips of the consumer, I don't want to have to go through several different sites to find what I want for my game, I'd rather have one source to go to and know that if I bought it once I can download it forever and it's compatible with all the online tools that I use daily.
One thing I forgot, I think that each digital tool should be connected to the book it relates to, buying the PHB will give you the the character builder with only the stuff in the PHB, MM will give you a monster builder with only the monsters in that MM and any kind of advanture builder will be linked to the DMG. Once the user buy somthing related to one of the tools, for example a book full of speciality clerics, than that info will be seamlessly integrated to that tool.
Warder