Here are some great photographers from the area that specialize in Nebraska (Michael Forsberg, Georg Joutras), Omaha/cities (Rick Anderson, Jim Burnett), wildlife (Thomas Mangelson) or have a wide variety (Joel Sartore - National Geographic).
I have liked forsberg for a while. He used to have a display at Eppley for a while.
And Mangleson - if you've been to one of his studios you'd be amazed at the color he reproduces - it is absolutely stunning!
I really like Michael Forsberg too. He has a great studio in the Haymarket District in Lincoln. USPS made a stamp from this photo:
Georg Joutras has a small studio in the Burkholder Building with other artists. Rick Anderson has a great website that has a nice selection of downtown shots from various cities. Jim Burnett is a local and I believe he sets up shop at the OM Farmer's Market in summer. Joel Sartore is a National Geographic photographer (many great photos) and did a great piece on Nebraska several years ago for the magazine. Thomas Mangelsen is a world-renowned photographer (his family runs the Mangelsen's store on 84th Street) and I think everyone recognizes this photo from his portfolio: