Stupid Invaders

Cheating Planet
Contains walkthrough by Lone Lines.
http://www.cheatingplanet.com/walkthroughs/s/stupid_invaders.shtml

GameFAQs
Contains walkthroughs and gameplay hints.
http://www.gamefaqs.com/computer/doswin/game/354448.html

Stupid Invaders
Official site, with story, characters, video, and downloads including postcards and desktop themes. Requires Flash.
http://www.stupidinvaders.com/

Universal Hint System: Stupid Invaders
Includes hints on finding rooms, and solving problems in the Abandoned House, Dung Factory, and Area 52.
http://www.uhs-hints.com/uhsweb/stupid.php