I know, I know, posting has slowed down of late. This is primarily due to working overtime and children's activities keeping me pretty busy. So, this will be short, but hopefully sweet.
First, I found what seems to be a pretty helpful site for 4E Dungeon Masters: Adventuringkit.com allows you to do three things: build custom monsters, build encounters, and string those encounters into full-on adventures. The monster builder seems pretty robust and easy to use. The encounter builder allows you to use those monsters and create a (very basic) map. Building adventures seems mostly limited to a few text boxes and links to the aforementioned encounters. If you have an Android phone, this guy has built a free app that pulls up monster stat blocks from the DDI Compendium (assuming you have a subscription, of course!), which is called KMonster. I would assume that KMonster and AdventuringKit work together pretty well, but I have yet to test that theory, as I do not have any Android devices. However, I will be throwing together some encounters and monsters using this software and I will post them up here when I have them completed.
Secondly, I found some really awesome stuff for the D&D Adventure System board games, Castle Ravenloft and Wrath of Ashardlon. These are Dungeons & Dragons games, and like every iteration of D&D, beg for houserules and customization. What is really awesome about these games is that it is incredibly easy to maintain game balance, once you've played the game a few times, while introducing new, custom, homebrewed goodness. Here is an article by Ninjadorg on the merits of solo play with these games, but really I'm pointing you to this article because of all the linkage to an abundance of additional material that is very easy to use with these games. In my opinion, a lot of the suggestions fix some things I didn't like about the games (such as monsters always winning initiative). Ravenloft and Ashardalon have been filling my D&D void lately, and I have been very excited to see so much homebrew stuff for these games, especially so much stuff that looks as good as the official WotC product.