Well,
I think I will just post what I want the DI to be
I have never been a regular consumer of Dragon/Dungeon Mag as they are hard to get by where I live... somewhere in Germany

I own a lot of Dungeon Mags, but I got those by buying a whole bunch of them at a time...
Basically there re three things I think would makethe DI great, a way of enhancing D&D:
1. Tools! I DM, and I tend to only use core content plus a very few non content feats for my monsters and npcs... why? Cause I only ue PCGen to create those! I want a fully featured generator for PCs, NPCs, Monsters, Treasure etc. (Or many small generators...) It would make my DM life easier.
2. Patches. I have the feeling balance in D&D today is considered to be as important as in Blizzards most famous games (WoW, War3, SC)... what did Blizzard do to get finely balanced games? They patch. Thats more than errata, you could provide "alternate" versions of spells, classes etc. to fix the games balance. That would not be everyones cup of tea, but those who want would be able to get a finely balanced version of D&D. (Might be a local tick, I don't know about that. What I know is, there are many many DMs and Players here thinking as much about balance as about anything else...)
3. Content. The Most important content to me would be adventures. Players like the obious crunch, but I think you need o be carefull with that, as many DMs do not like to be suprised by the newest Feat. And making DMs read all the new stuff is a way of hightening the DM load, something no sane person wants, I think.
What I would also like to see would be some kind of nerver ending Unearthed Arcana. (Rules, Races and Classes Variants that can be used to create a different campaign from time to time.)