I did a bit of cartography work. Maxed out a map, with the spawn at center. Took some screen shots.
Red line is the underground tunnel from spawn to Bob's Base. The red dots with numbers are the other bases I encountered.
0 is bob's place, 3 has a sign that says its Vnieminen's place

0, Bob's Base: (biggest one I think)

1: (did not get the best picture of this one :P )

2: (this one is pretty big as well, haven't explored all of it)

3: (small but cool)

4: (caught this one during a sunrise, with the forest in the background, thought it looked good)

So, who's is who's? I imagine it possible I missed someone. since I stayed generally within the range of what the map was set to.
Exploring with a map to fill out is one of the more enjoyable things to do in Minecraft IMHO. That and in the servers that allow it, player on player violence.
Also, Last time I tried, the server wasn't responding, it down? as soon as I can get on I'm going to make a nether portal. Chyka told me that he's pretty sure nether is on.