BTC Bitcoin Nodes: BTChttps://bitnodes.io/Bitnodes is currently being developed to estimate the size of the Bitcoin network by finding all the reachable nodes in the network.
Interconnections aren't documented anywhere that I know of.
Information about other 'tokens' should be asked about and discussed in altcoins section, but since I like to compare Bitcoin's decentralization to the one of the 2nd largest marketcap cryptocurrency, I'll drop this here as well:
Ethereum nodeshttps://ethernodes.org/history