This blog chronicles a DM's early attempts (starting about three years ago) to start playing a DM. This post includes a host of very helpful advice and information. I'm particularly excited about his made-at-home tokens and status markers.
Roving Band of Misfits
This seems like a fun, general D&D 4/e blog. They have a very good podcast as well that I'm now subscribing to. I much prefer it over some of the other offerings I've tried. They do some fun crafts, like this cheap beholder miniature. I'm also really diggin' their Two Page Mini Delves series (I'm linking to the second in the series, which is fairly new). Since my "campaign" will invariably need to involve the use of very small dungeons and such, these are perfect...and have a nice flourish of creativity that keeps them from being a simple hackfest.
This is a site that is specifically dedicated to providing tips for DM's. He is hawking his books via the site, but his content is very good and very helpful. I was very happy to find his "Start Here" link, which lists many of his more helpful posts. His 4/e buyer's guide very helpfully turned out to recommend exactly what I've already purchased, so that was reassuring...and it helped me realize that I will want to get that monster vault at some point, along with some tilesets. I may buy at least one of the books on his site, as the freely available stuff seems very good.
This is a newer site, but it's neat. Basically, the guy is posting some of his many dungeons that he has created. They're absolutely lovely, and should be printable for later use should I decide to use them. I would love to get a hold of the mapping software he uses, though apparently it is no longer downloadable.
That's what I've found so far. Any others I should be watching closely?