All Night Nippon -  Late night radio show carried on most Japanese stations (in Japanese)
Asian Broadcasting Institute – Japanese DX Club, site has information on MW/SW/TV/FM broadcasting in the Far East (mostly in Japanese, some English) 

Australian Radio DX Club - Information on DXing Down Under, from Australia's largest DX club.
Australian Broadcasting Authority - government agency regulating radio/TV in Australina

Australian Broadcasting Corporation – Includes information on their AM/FM/TV networks 

DXing China (1000 Lakes DX Page) – Links to many Chinese MW/SW/FM/TV web sites, plus other sites about China. 

Hawaii Radio & Television Guide–Comprehensive site on Hawaiian AM/FM/TV broadcasting 

Indonesian DX Club - IDXC – Very good site with loggings by Indonesian Dxers, information on stations, and other material (Indonesian/English) 

Nagoya DXers' Circle - Japanese DX Club, site includes several interesting listings, including an extensive list of Chinese Stations (mostly in Japanese, some English) 

NAB-(The National Association of Commercial Broadcasters in Japan) – Includes addresses and links to all commercial broadcasters in Japan 

Pacific Island Broadcasting Association – Industry group with information on stations in the South Pacific, including links and addresses for several stations 

Radio Marketing Bureau (Australia) – Australian broadcast industry site, with links and e-mail addresses for many Aussie stations
Voices of Distant Countries - DXing from a Russian perspective by Dmitry Mezin

Vostochnoe Radio – Comprehensive list of Russian Far East stations 

South East Asia on Medium Wave – Long List of SE Asian MW Loggings by Alan Davies
Southern Cross Syndication - Distributes several networked programs throughout Australia

South Pacific DX Resource– Articles and listings on New Zealand and South Pacific radio. Includes several interesting historical articles.

Digital Signal Processing - Good overview of DSP from Tuscon Amateur Packet Radio
DX Notebook - Antenna Page - Links to antenna-related web sites
DXer.Com Propagation and Solar Flux - Collection of Links
eHam.net - Collection of ham resources, including product reviews, propagation, ham links, articles, and other information
Hard-Core DX Antenna Page
HFradio.org - Propagation Page - Current solar and geomagnetic reports
ITS High Frequency Propagation Models  - Public Domain HF propagation modeling software developed by the U.S. Dept. of Commerce.  Very useful once you learn how to use it.  Mainly for shortwave, but also seems to work for medium wave frequencies.
Javaradio.com  - Web-controlled receivers, mostly located in the US and Europe
KB1GW's collection of Beverage Antenna Information
K3KY's Low Bands site -  Antennas and receiving techniques for use below 10 MHz
Mark's RF Circuit Building Block Page - Mark Connelly's collection of r.f. construction projects.
Minidisc.org - Minidiscs are a great way to record your DX
QSL.net Propagation Reports - Current solar and geomagnetic reports

DX Monitor - Freeware program that generates azimuthal maps and shows distances, bearings, sunrise & sunset times, and other information
Geoclock - Versatile mapping program showing areas of darkness and daylight
Jane's Oceania Home Page- Huge site devoted to Pacific Island culture, geography, travel and history
Microsoft Terraserver - Aerial photographs and topographic maps of the entire U.S.
National Geographic Society's Map Machine
PostInfo - Postal Authorities Page - Postage rates and policies for many countries
SwissInfo -  Local Times Around the World
University of Texas - Perry-Castañeda Library Map Collection