I'm more than a little excited to see how it all shapes up. I will most likely be a frequent visitor to your site. I respect both you and Joel greatly. Since he is soliciting ideas for the site, here are mine.
Here is something I would love to see; a series of articles on best practices. Meaning, if you need to show a table of data (repeating rows), should I use a repeater, or a gridview? Why? What if I need to add a checkbox into a column (or make it a new column)...how do I do that in a way that is cross browser compliant?
Beyond that, what I would NOT like to see is a website that is something like what Joel described in his article on how MS lost the API war...please please please do not become an MSDN site showing off the latest aluminum bullet every couple of months. Show me proven ways of accomplishing well defined tasks, with good explanations of why.
Also, I would hope that your site doesn't get a rush of quick answer artists trying to build "karma" points without doing any teaching.
I'm not sure if you or Joel ever spent any time on the old VB programming newsgroup microsoft.public.vb.general.discussion, but there were a group of about 10-20 developers who really cared about honing their craft, discussing the "best" solution, teaching new users who showed a desire to learn (like me).
That is a site I would frequent.