Professional

Science Direct, Digital library for papers published by Elsevier
MeSci, Museum of Emerging Science, Great science museum in Tokyo
LaTeX FAQ, FAQ for the LaTeX document preparation system
MATLAB FAQ

Company websites

University of Twente, or in dutch: Universiteit Twente
Airbus, aircraft manufacturer
SCK.CEN, the Belgian nuclear research center

Family & friends

Entzinger.nl, family homepage
Huize Marsupilami, webpage of my student-flat
Wout Ruijter
Jeroen Hol
Nynke van der Vliet
Rene van Helden
Maarten Fonville
Olaf van Zandwijk
Werner Breitfuss
Tobi Rossteuscher & Mae Rose Sumugat
Mae Rose Sumugat (Photo gallery)
Mae Rose Sumugat (...the far end of the spectrum)

Photography

Yann-Arthus Bertrand, French photographer for UNESCO
TrekEearth, Learning about the world through photography
Kodak - Taking great pictures, lots of useful hints for photographers

Cooking

Encyclopedia of spices
CookingForEngineers.com, recipes in table form
Ingredients dictionary, list of ingredients with their photos (cooking for engineers)
Smulweb, Dutch site with recipes (need login)
Epicurious cooking recipies, cooking techniques and food and wine dictionaries


Web-design

W3C Validator, check whether your webpage complies to the standards

Cascading Style Sheets

Tanfa CSS-popout menu, tutorial to create a menu like on this site
CSS-fixed menu bar, to make a menu bar that doesn't scroll with the page
The CSS playground, look for the alternative styles to see the power of CSS

Dynamic webpages

PHP Manual, API for this scripting language
MySQL, database server program