Mail order is not all that common in the Netherlands. Most companies specialize in one line of products such as clothing, health products, exercise equipment, etc.
Aanbiedingen van TV
Health products and exercise equipment
http://www.aanbiedingenvantv.nl
KliNGEL
Men and women’s fashion, shoes and household goods
http://www.klingel.nl
Neckermann
Fashion, gifts, electronics and household goods
http://www.neck.nl/
Bader Online Nederland
A lot of fashion but a whole lot of other stuff from household to electronics to health and beauty
http://www.bader.nl/
Mailorder solutions
An umbrella group for some very specialized web stores; mostly household goods but some clothing also
http://www.mailordersolutions.nl/
HollandbyMail
Send the folks back home some of your favourite Dutch treats
http://www.hollandbymail.com/