Its really just an easy way for buyers to see what you have.
Its literally a sheet of paper (or online doc) that has a photo and info and price.
it can have the wholesale & retail price, dimensions, color options, sizes etc.
Just organize the info in a concise and easy to read kind of catalog, or brochure. Except a line sheet is not a brochure because its concise.
I just uploaded an example of mine that was a template from trunkt. I took out the pricing, but you can see the format here:
http://www.flickr.com/photos/popko/8495134167/in/photostreamI decided to give them each a number (#101 etc) just so it would be easy to discuss them this way.
Hope this helps you a little!