RetroShare has also built-in mails and messaging. There's a thread somewhere with lots of "friends" to make. Folks run their nodes for free so far, without Bitcoin incentives. But maybe such a feat would boost the network significantly.
No one in that thread was reachable. They don't actually run retroshare at all, or if they do ever fire it up they presumably notice as I do that there is no one online to connect to thus they shut it down again as useless.
I even got a private message recently on these forums from someone claiming they will run it almost all the time, so I fired it up, saw that still there is no one to connect to, added them and waited and saw that they too were not online so unable to be connected to, and shut it down again.
I had 28 or more people from the thread PLUS another over 20 people I friended from being able to see the connections of the 28 in the thread, yet all of those second-step connections also were offline.
Meanwhile I have always found connections no problem when I fire up i2p or Tor or Freenet. So compared to any of those three I basically do not find retroshare worth bothering with. The whole point of a network is connections. Without connections there is no network.
Even if the person who resorted to PM to get me to add him or her does turn out to be online they next several times I fire up retroshare, that won't convince me to bother with it. When I see the majority of the people in the thread and/or the majority of the people I reached through them online every time I fire it up I might reconsider whether it is worthwhile.
-MarkM-