Ask HN: Best way to set up family webapp?

As the family "geek", I have been drafted to set up our family website. I am happy to get this going, but ONLY WITH existing offerings (I'm way too busy with my own work to start programming this.)

We have hundreds of family members all over the U.S. Many in the 4th generation have no idea who the rest of us are and how we are related. We would like to share messages, old photos (even some video), and plan our 100th anniversary reunion for 2010.

Ideally, I'd like to set something up so that the community can "take over". I don't want to get stuck planning a family reunion and get stuck in between lots of differing opinions. Previous attempts by others have never gotten off the ground.

I've already started a family tree at geni.com and I'm thinking of expanding that, unless there's a better approach.

Anyone here with similar needs? What have you done?