I have connected 3 vaults (yes, I know I shouldn’t have) and added http://mystats.safenet/ site which display some statistics about the network.
The total number of vaults is estimated with empirical formula defined here, but 3 measuring vaults are not enough and only give a rough estimation.
Some averages on data in my 3 vaults are also displayed. Interesting extrapolations could be computed but uncertainty is very high. For example, the formula for the total number registered users would be: Estimated total vaults * Login packets / 8 (~ 365 users at the time of writing).
The site has no javascript but has an automatic refresh every 15s.