If you already have a design ready, you can use Ponoko
https://www.ponoko.com/
If you only have an idea for a design - get into your local phone book and find engraving/trophy shops. Most have a laser engraver - or at least access to one and will be able to help you convert an idea into an actual useable design. Those issues can be easier to work out when you are talking to a person directly.
If you don't have a local source - I have used Pololu in the past and they were good enough. I needed some copies made of a part...shipped them the part, they created the design, cut the copies and mailed it all back.
http://www.pololu.com/catalog/product/749