I'm going to be a bit blunt here: your photography isn't the kinds of stuff clients who buy stock/microstock go for. In 2011, the vast majority of stock photography is used to sell business products to business people. And if it's not that, it's used as a source of images to be composited with other images.
I've worked in interactive and print advertising and design for the past 13 years, on literally hundreds of campaigns for international brands the world over.
Here are things we bought: people in suits doing business things (all white, we're in europe); people in suits doing non-business things - like jumping, running, hanging off a ledge; pretty, neutral spaces like kitchens, offices, living rooms we could put people and products into; an amazing amount of travel photography with clearly visible landmarks for an airline; landscape photography that included sweeping vistas that we could, again, place items into. Give me any of these things in a cohesive series and I will love you to death.
Some things stand out in your photography that would cause me to look over most of it, even if I had a market for the subject matter. Post processing for a look either by defocusing elements, color tinting the image, adding blur - I want sharp objects I can cut out/composite with other objects. I want my starting images to be as neutral as possible.
There's a huge difference between people liking your work on flickr and actually buying your work. For someone to buy stock photo, they have to be able to use it as an element of making more money for themselves. Look at your photography and ask yourself if this is the kind of work you can imagine being used by people who actually lay out the money to license those images.
Ask the microstock houses what kind of photography they need more. I almost tried selling stock on a now defunct stock site. They had a great list of what they had more than enough of, and what kind of stuff they needed. Number one with a bullet is always: "People in suits doing things."