Here's some updates from the Multiplayer server I play on:
My Base
Ain't no creepers getting up here! (Only way in is through the tunnels in the water or that little sky bridge)
Tunnel connection to towers
The Sky Palace I built at the top
A bridge to nowhere (so far). I just wanted to make a bridge SOMEWHERE.
The girlfriend is doing some pixel art for me.
The server admin tested out the ion cannon, and was like "what the hell do I do now?" as he surveyed the aftermath. I suggested making an underground base out of it. He took the idea and REALLY ran with it.
There's 4 other people on the server but I haven't bothered to check on them in some time. They haven't been too active...well, two of them were, but all they've built is like 50 block high walls around their bases.