Synchronet has a small toolkit for finding and contacting other users — those currently online and those who've used the system in the past. Most of these are loadable modules invoked from the command shell; some of them are also accessible via control-key commands from anywhere on the BBS.
Ctrl-U from anywhere on the BBS lists users currently logged on: their names, the nodes they're on, their connect type/rate, and what each is doing right now. Default module: nodelist -active. See Control-key commands.
/L from the Main or File Transfer prompt — or from within a chat session — lists the activity of every node on the system, including inactive ones (showing their last-known state). Like Ctrl-U but more comprehensive. Default module: nodelist.
Ctrl-P from anywhere lets you send a private one-line message:
After Ctrl-P you'll see a list of online users and their node numbers. Enter a node number, or A to broadcast to all users on the system. Type your one-line message and press <CR>.
Default module: privatemsg. See also InterBBS Instant Messaging for cross-BBS messaging.
U from the Main prompt opens the User Lists module. You're prompted for which list:
Quick keys: [UU], [US], [UL] from the Main prompt.
Default module: userlist.