I came across a couple of interesting articles, books, and a program:

Dave’s Mapper – A top down map generator. Can’t really use it for anything serious, but it may give you some inspiration when you try to come up with a floorplan. It is actually remarkably UT’ish/Quake’ish what it generates :)
Modular Environments in UDK – A tutorial from my friend Thiago Klafke on creating modular meshes for use in the UDK (or other engines if you wish).
Motivating Players in Open World Games - An article on game and level design in open world games from someone from Bethesda.
Spacescape – Free star texture generator.

Also I just bought a couple of books, two most notable ones are:

Pictorial Encyclopedia of Historic Architectural Plans, Details and Elements – Reference guide with nothing more than side and top sketches of parts of historical buildings.
Architecture Form, Space, and Order - Very readable. Just enough text, and thousands of pictures. Really nice book if you want to developer a better understanding of architecture and you don’t want to read hundreds of pages of heavy academical text.

Also have two game design books to still go through, and a book on castles. I figured since games are usually about assault/defend, lets read some in-depth info on castle design.