World building to me is one of the most adventurous and fun things about writing fiction. Creating characters, their cities, their culture, deities, technology, and essentially making a whole world of my own (or several worlds) is pretty exhilerating stuff.
A lot of my world-building is very inspired by our own world history and folklore, which I guess is quite an indicator that I have a obsession with the past. I won't apologize, because it leads to things like Richard Armitage looking dashing in a suit walking through a cotton mill playing on my screen.
What I try to do when I world build is to keep them seperate worlds, but try to retain my "voice" as an author. This does lead to a lot of clutter in my head.
I have one world that is loosely inspired by Victorian England in terms of culture and techology, yet their kingdoms and rulers are a throwback to much older times or great myth and the idea of many gods/goddesses. Also, one kingdom alone never gets warmer than 60 degrees. Don't ask, I blame living in Scotland for this idea of a quirk sticking in my head.
I have another world that is very fantastical yet is inspired by Rennaissance Europe. Courtly love, intrigue, romanticism of that time...there's a lot of elements I like drawing from that period in history that in itself are great stories as is.
When I really get into a project, I will map out a world so intricately as if its a history/anthropology report. I like to think this is because I am so proned to being scatter-brained that it keeps my organized. It also helps me outline where I want a story to go.
Anne Bishop is an author who I think is very excellent at world builing. Her Black Jewels Series, especially the original trilogy, are very amazing in the way she set up this whole caste system and world and it just blew me away.
Neil Gaiman is really great at it too, but then that man could write a laundry list and I'd fangirl it.
What do you guys do to world-build or where do you get your inspiration from? What authors do you think excel at this?