Sampa, a Seattle Web startup, emphasizing genealogy with a new online tool for building and sharing family trees. The free tool was to be launched today (Thursday) at noon.

I wonder how many small startup offering ambitious tools for Web sites, blogging and social networking will turn their attention to smaller niche markets.

Sampa's making a clever, viral move because users may loop their relatives in to collaborate on building the trees. Presumably they'll keep returning to update the trees as their families evolve.

Here's how the change was described by founder Marcelo Calbucci (who left Microsoft in 2004):

"Sampa used to be a generic Web site building tool. More and more we want to move that into a purpose-driven website solution for families and groups of people that want to share with people they already know.''

That's a change of perspective for Sampa, which was built to be a horizontal platform.

Sampa's service is free and the business is supported by ads. Calbucci said they may add a premium service in the future, but right now the company is trying to raise $500,000 of seed capital.

One use of the proceeds would be to expand headcount by 50 percent - from two people to three.