You can park at the baseball stadium for 25. The indian reservation is also a popular spot and has a bit more of the college aged crowd, but it is always a good time. I believe it is 20 dollars a car, and is pay lot only, no passes. The tailgating is different here than most places in that it is spread out over a vast area. Most of the tailgating takes place to the west of the stadium under the bridge or to the north in the bottoms neighborhood and the reservation. I would recommend just walking around and finding places. There isnt much to the east and south you get into downtown, there are donor lots spread out throughout campus that have tailgating as well.
For those of you who are thinking you want to go to the bars, wait til after the game. Go walk around the tailgate lots to the west of the stadium and you will be wined and dined, you will have a good time. Save the bars for post game, as thats when they get the most action.
The main strip of bars is located on O St between 12th and 15th. Off O st to the north, there is the Single Barrel, which has a mechanical bull and is a good time, as well as the Embassy Suites, which gets a good crowd. They have an outdoor beer garden which usually has live music of some kind. All of them is within walking distance to the stadium. Barrys is the newest bar/restaurant in DT Lincoln and has a rooftop bar as well. I have not been yet but I hear it is pretty cool. It is located between DT and the haymarket district.
The Haymarket district is more of a restaurant/bar area, and there are a variety of things down there. I'm not sure how good it is pregame, but I imagine there are a good amount of people down there post game. Also short walk to stadium.
If you guys have any questions I'll be more than willing to help out. GBR!
For more info, take a scroll through this thread-
http://www.huskerboard.com/index.php?/topic/59994-gameday-info-for-lincoln-visitors/