I similarly think of this every year when I go on an annual camping trip with a group of friends. We have a short group list on a website that we use, but it would be helpful if we could edit that and add to it. Each year it is inevitable that something is forgotten or we talk about something in January but fail to remember it in August/September.

I often check my gear against lists that are published by camping supply companies (Coleman, etc). Much further down the line, it might be an interesting business model to allow for "sponsored" lists.