I actually had this idea a few years ago but never got around to building it, so I'm glad you're making it happen.

At my previous startup I hacked this manually by taking a screen grab with Evernote once a month.

I've heard Alexis Ohanian mention he is thankful for having the foresight to take screen shots or early reddit builds too.

I'm sure a lot of startups would find this useful for capturing the journey of the product and then later nostalgia.