Hopefully this will be open source, so not only a web service that one has to rely on, but something that could potentially just read the blockchain + a file with names for individual addresses and then generate such graphs (or input files for them) on the fly.
Actually, it shouldn't be too hard to do with Python, Armory (or Java + bitcoinj). It seems that Gephi needs a "GEXF" file (https://gephi.org/users/supported-graph-formats/
) as input or it might be possible to simply create the graph from within (using https://gephi.org/tag/python/
+ access to a blockchain library).
One problem might be, that there are probably already close to or more than 1m unique addresses in the blockchain, so some collapsing might have to be done (e.g. if a transaction has more than 1 input address, consider them belonging to the same entity).
Also Gephi seems to support data source + import plugins, maybe it's possible to write one of these for Bitcoin style blockchains (so one could also analyze Namecoin etc.)?