One of my favorite things about web consumerism is the way it facilitates what's known as 'light customization.' Generally, this is accomplished with Flash-based geegaws that somehow encourage really hideous color combinations. I'm hoping to revise this post as more examples of this kind of thing occur to me, so if you encounter others, please let me know.

Shoes:
Converse--custom-colored Chuck Taylors
Customatix--custom-colored sneakers
Nike--custom-colored Shox, Dunks, etc.
Vans--custom-colored Old Skools, slip-ons

Clothes:
Neighborhoodies--t-shirts, sweatshirts, etc. with custom colors and logos
Lids CYO--baseball caps with custom colors and logos
Lands' End--shirts, pants, etc. in custom colors and dimensions

Bags:
Freitag--messenger bags
L. L. Bean--tote bags, daypacks and messenger bags
Queen Bee--no longer makes custom items
Timbuk2--messenger bags
R.E.Load--more messenger bags

Diamond rings:
DeBeers--Note: Your diamonds have blood on them.

Multi-tools:
Gerber--Alas, no more custom multi-tools. Just for that, Gerber, I'm going to start trying to do for 'Leatherman' what people did for Kleenex and Xerox.  ¶ 8:57 PM