Make:

@The NYC Toy fair 2008 there weren't that many customizing companies but I did meet the folks from U-MARQ - they make a $7,000k-ish computerized engraver - with these you can engrave: small items such as jewelry, rings, charms, and pens as well as large items; wine bottles, plaques, trophy's, tankards, etc... on gold, silver, platinum, stainless steel, titanium, glass, plastic, wood and soap. I use a laser cutter, but there are things (mostly shiny items) that tend to look better if you use a physical engraver like the ones from U-MARQ.

You could probably get one of these, or build your own and do some nice work on iPods, iPhones and more as business.

More:

• U-MARQ - Link.
• Videos - Link.
• More photos of U-MARQ @ Flickr - Link.
• Giant set of NYC Toy fair 2008 photos @ Flickr - Link.
• MAKE's coverage of the NYC Toy Faire 2008 in one place! - Link.