My two cents:
* The tunnel walk. One of the premiere entrances in college football, although definitely not the best. Started in... '94 (I think?), when we got our first two video boards, and the players come out of the locker room and into the stadium to 'Sirius' by Alan Parsons Project. With new technology, and new video boards (can you believe we have five of them now, with one being one of the biggest in the country, not to mention the ribbon boards) the entrance videos have changed over the years. Under Callahan, they started doing different things. In '06, every week there would be three players saying something inspirational and then at the end they would all say "I play for Nebraska.", then cut to a clip of Keith Jackson saying something to get the crowd pumped up. In '07, we used a remix of the Saw movie theme, made by Nebraska's very own Mikey Bo, and it had a god-awful entrance that involved a plane and some panzy pinkshirts or something like that, and everyone hated it. Now, however, we've gone back to basics, just showing important stats and highlights in the program's history and getting everybody ready for the game.
* Sellout streak. Every single game since 1962 has been sold out (304?). Not much else to say here, except that statistic is insane.
* Husker power. One side of the stadium yells "HUS-KER", other side yells "POW-ER!". Gives me goosebumps every time, it sounds amazing when the incompetent cheerleaders actually get people doing it.
* Student section holding up their shoes. This started when Adi Kunalic became our kickoff specialist his freshman year in '07, because he would put nearly every single ball either into or completely past the end zone. Don't know if this is done anywhere else, but I find it pretty humorous.
* Blackshirts. Started back in the 60's, our D Coordinator needed different color jerseys for the defensive players, and the local sporting goods store only had black ones. Turned into a tradition to hand out "Blackshirts" to the starting 11 defensive players, which was a big deal because we always had good or great defenses. Under Callahan, the tradition was tarnished big-time since our defense sucked, and when Bo took over he changed the tradition. Now the players have to earn the Blackshirts through the season, instead of just getting them by default. In '08 it took all the way until the Kansas game (in which we actually gave up 35 points, but the defense still played their tails off) for him to give them out. Last year, he gave them out after an unbelievably inspired Missouri game in the rain. Also, Alex Henery (field goal kicker, essentially the best in the country) was awarded a Blackshirt last year.
* I don't think the students/players sing with the band after games anymore. Believe that died with Callahan.
* We are awesome?