There have been some good ideas in this thread so far!
As for me I would like to see support for some of the "dead" settings. I was actually talking with a friend and he had a great idea. What Wizards should do in terms of Dead settings is have each year be a theme. So for example 2007 would be Greyhawk themed and they would release a campaign setting early in the year and have another book or two ready for production. If the campaign setting sells well, they could release the other books. If it doesn't they could scrap them.
They could do this every year and bring out minimal support for a setting. When they are done a few years down the line they could determine if they think any of these settings are a viable business opportunity.
I realize it is not likely to happen but I think it would be cool if it did. I think most fans that want support for old settings don't want 6 books a year they just want a revised campaign setting and maybe an adventure or two.
Other than that I would like to see an new OD&D collector's boxed set. The three books, printed exactly as they were with maybe an additional book that could contain stories from people who played it when it came out. As a collector I would think that would be a special thing to have. Plus I don't have an original set and I never seem to win them on Ebay when I think to try.
-Shay