I'm interested in seeing what other people are building. I'm building a sky 'world' right now, probably pretty generic but I'm a newbie so. :P  
 
My work so far. 

Well, in building, I'm trying to make a glass mountain that has mass farms, ect. It's coming very slowly, but I'll do it dammit! 

I plan to work on an underground city connected by a subway with some underwater buildings.

I haven't decided yet. I've started a dozen or so worlds and deleted every single one after a few hours. A game with so few objectives really isn't as much of my thing as I had expected.

Mine will be a treetop city, until I have a better idea. I started with a two story lakeside home with walkways into the trees, and that works great for moving around at night.

" I started building an underground city like in Arx Fatalis. I stopped because it took me almost an hour to build a crappy shack and it got blown up by something. "

" I haven't decided yet. I've started a dozen or so worlds and deleted every single one after a few hours."

is there a way for me to go into build mode instead of survival?

" I plan to work on an underground city connected by a subway with some underwater buildings. "

" is there a way for me to go into build mode instead of survival? "

"I've just decided to take a nice looking mountain and hollow it out.  It's actually two mountains, connected at the top, but both will be hollowed out eventually.  A neat thing about them, is that there is a tree at the top that is naturally touching the highest point in the game.  But yeah, i'm just going to take care of the mountains, then work my way from there. "

I just started last night, so it'll take a while (I'm still getting a handle on things), but the plan was to build Castlevania (the castle).  Not far from where I started I found the perfect cliff - a treacherous overhang that looks like it should collapse.   I just hope I can build high enough.  I'm building a tower of my own first, to get an idea of what's involved, before I get started on the real thing.  After that?  I don't know.