I know you're not asking for C+C, but I must tell you -- your work shows much potential, but there is one thing that ruins it all: Your sprites have *very* dull colours. In other words, they tend towards grey -- it looks as if there is a layer of smoke over them. I would suggest looking into improving that aspect of your work. You need to learn to use colour contrast between adjacent pixels to make your sprites "pop". Study the bitmap brothers work eg. Mark Coleman's work on Chaos engine. Remember: One mixed colour is not the same as two component colours side by side. That is a common theme in traditional painting, as well.
EDIT: And -- look at your work on a range of other monitors, not only your own. If you can, that is.