[johnfactorial]

A short list of those tons would be wonderfully helpful to share. :)

[xtracto]

From the top of my head:

I2P Freenet Tor Zeronet

[SkyBelow]

I think by a technical definition, every company intranet would count (minus some poor security configurations). But that doesn't really seem to be a fair companion to the more commonly discussed dark web.