The American Heritage Dictionary offers two distinct definitions of a nimrod -- either a hunter, or a person regarded as silly or foolish. The dictionary goes on to explain that the second meaning probably originated with the cartoon character Bugs Bunny. The wily Bugs used the term in its original sense to refer to dithering hunter Elmer Fudd, whom he called a "poor little Nimrod." Over time, however, the "hunter" meaning got dropped, and the "dithering" connotation stuck.
Nimrod was in fact a Biblical figure -- the great-grandson of Noah. He was a haughty king who declared himself a "mighty one in the earth," founded the great city of Babylon, and presided over the construction of the mythical Tower of Babel. Nimrod was also a renowned hunter, though at least one source we found claimed his game of choice was not animals but men, whom he would enslave upon capture. Whatever his prey, his name became synonymous with a skilled hunter.
And for the record, the University of Tulsa publishes a well-regarded literary magazine called the Nimrod International Journal of Prose and Poetry. They are actively seeking submissions.