To answer the original question - how deep do you go into your worldbuilding - I'd say it varies. My primary aim is to create the feeling of a full, complete, living-and-breathing world, but obviously I can never actually complete a world. Instead, I try to create an illusion of complexity. I work out the general outlines of what my countries, cultures, etc. are like, but then I try to attach small, specific details to them, details that evoke the feeling that there's more to it.
Of course, in just a few areas, I still do actually go super in-depth.

I only have the basic outline of the history of Thomorai, a continent in my world, for instance, but I know a certain modern Thomoraii video game company intimately: its background, all the games it produced, its end, its employees and all their personalities and backgrounds and futures, its reputation, where its offices were, what its logo was...I'm a worldbuilder at heart, so none of this has relevance to any of the stories I've written. But the point is that if you can get the general outlines of your world and then add a few evocative details and have a few areas really fleshed-out, I think you can make it seem quite complex and layered. Also, if you add a bunch of those little evocative details, they tend to pile up and become detailed, fleshed-out areas of their own.

To answer the question that a lot of the posters above me seem to be answering - how deep do you go in your worldbuilding before writing, and as you're writing - I am, again, a worldbuilder at heart, and so I tend to have a lot worked out before I write...but I also tend to do things like you guys said:
Mistress Rwebhu Kidh wrote:
StormCry wrote:
I have found, though, that most of my world building inspiration comes as I write the story. If I need to describe a landscape, I stop and build a perfect picture in my mind before continuing. If I need to explain a custom or a city or even a person in the story, I stop and work out their history. Sometimes I will be writing out something and it will hit me suddenly: "Oh! You know, it would be really cool if..." So, needless to say, I don't build my whole world before I start writing the story. I start with a couple of cities and important places, and then I go from there. The rest comes later.
That's how my worldbuilding usually goes, too. The only time I actively worldbuild in a way that is not related to a story I'm working on is when I get so excited about some idea that I have work it out. * grins *
I often come up with great ideas while I'm writing, and I also often come across holes in my world as I write...so I make stuff up as I go!
