I think it was almost ten years ago that I coined the phrase "The Uniform" to denote the standard male business casual dress of light blue oxford shirt and tan khakis. (See the Steve Ballmer videos for the most appalling example thereof.)
Me? Well, I try to change it up a lot. However, my go-to casual mode of dress is:
Baby blue t-shirt, either a plain l/s or s/s with interesting print
Dark blue jeans
Black suede Adidas Gazelles or brown casual shoes (Kenneth Cole Reaction or Unlisted, usually)
For the dress casual look:
Nice dress shirt or v-neck sweater, either a good solid color or interesting striped pattern
Grey slacks
Black dress shoes
I used to just wear black, black, and more black. Now I typically reserve the black for my jacket, shoes, or occasional t-shirt. Wouldn't mind finding a good pair of black jeans again, or some slim-fitting black trousers.
My feelings on jeans are conflicted: I love how comfortable and versatile they are, but it drives me nuts when I go out and notice that everyone else is wearing blue jeans as well! Seeing row upon row of semi-faded blue legs on the bus is kind of... depressing, actually.