It's a good idea. Why not ask startups to upload a startup.txt (as opposed to robots.txt) to their web root and collect from that? Pre-filled text forms can be downloaded. Also, as with CB, collect data on individuals through a similar opt-in. Enable users to ping your site when it's ready to collect.

You could have a "traction" stat and ask for a JS snippet be installed on homepages or a set of pages. Old school and unreliable. Registered users is also a good way to assess traction. Not sure how that information could be readily obtained.

In my previous comment I mentioned attaching a crypto address to domains - you could do that too. That'd be interesting. One feature you could add long-term is crowdfunding. Either for new features, code releases, media, documents - whatever.

Crowdfunding activity on startups and individuals would be a great way to measure traction.