Great ideas and I would like to make another couple of suggestions.

1. Go to your customers and evaluate your value proposition. Many times you find benefits that were not expected and can be utilized by other niche markets. The Moosewood cookbook was originally a hippy vegetarian rag, but by uncovering that they had a following of foodies that loved a couple special dishes, they re marketed it to the entire cooking population.

2. Look for niche markets that parallel your core customer base. Often this will afford you an unbelievably minute amount of tweaking if any at all.

I would just add that Internet marketers need to add a separate web site or at least a separate sales page for each target market.

They also need to do market research again because the best appeals for each target market is different. I discuss some of the ways that target markets differ on my blog under “market segments.”