These firms appear to be reputable, but no endorsement is implied. There may be other, better sites. Investigate for yourself. These links are provided in response to numerous inquiries and I regret that I have no further information on this topic. I would like to learn of Maryland firms which provide visa sponsorship.
Jobs lists job links for each county.
An excellent site. Two commercial sites for members of the military aiming to start new careers as civilians. University of Maryland College Park Career Center. A good place to go, after you've exhausted the Maryland Careers site. Anne Arundel County High Technology Council, with links to members.