Nebraska was in 4 "national championship" games in 5 years winning three of them. I should have included Miami, Florida State is close to that (might have been included), and Tennessee is no where near that level.
The period you cite is 1993-97.
Two things:
1) it wasn't until the following season (1998) that the BCS started and thus were guaranteed #1 vs #2 matchups in bowl games, and
EDIT: importantly, there was still a Bowl association prior to the BCS, which was trying to accomplish the same thing, and it had all the big conferences at that time - including the Big Eight - but just lacked the Big Ten and PAC-10, who finally joined in 98 and made it the BCS -- so actually I have to concede this point as invalid, for the most part
2) the first three seasons of this period (93-95), Nebraska was still playing in the
weak Big Eight. And actually, the pickup of the Texas schools for the last two seasons ultimately mattered little save for losing to Texas in the conf champ game in 96.
So let's look at these seasons:
1993 - went 11-0 with a fairly weak schedule, facing only two ranked teams during the regular season: Colorado in Boulder (CU was actually very good in the early 90's, I give the B8 credit for that) which they won by 4, and OU in Lincoln which they won by 2 TDs. End regular season #2 and happen then to play #1 Florida State in the Orange Bowl. Fair enough, though they lost.
1994 - went 12-0 with a tougher schedule, vs #24 West Virginia played at the Giants (NFL) stadium, and at home vs #13 UCLA. At #16 K-State, and got #2 Colorado in Lincoln. OU down that year. Most of those were nice wins. Played #3 Miami in the Orange Bowl. They would've had to play Penn State for an actual title game. But they were given the #1 ranking by the voters.
1995 - went 11-0, no ranked teams in non-conf, for conf games had #8 K-State at home, went to #7 Colorado, and got #10 Kansas (oh hey, Mason) at home. Ended up playing #2 Florida in the Fiesta bowl. Agree this was a real natty.
1996 (Big XII) - actually, their only loss during the regular season was at #17 Arizona State. Had at #16 K-State and home vs #5 Colorado. Maybe could've still made the natty, but they lost in the Big XII champ game to Texas. So ended up #6 after beating #10 VT in the Orange Bowl.
1997 (Big XII) - won at #2 Washington in Seattle, great game obviously, then home vs #17 K-State was their only ranked regular season game. Beat #14 Texas A&M in the Big XII champ game. Then beat #3 Tennessee in the Orange Bowl. The AP voted #1 Michigan as national champs (not surprisingly, this was
also their last national title, like Nebraska), while Neb had to settle for the lower Coaches poll #1 spot. So I don't even necessarily recognize this title, as they would've probably lost to Michigan.
After going through this exercise, I admit I have more respect for it than I thought I would going into it.
But I still hold that this is not some special feat.
Nebraska benefited
massively here from having a very weak conference schedule, which included Oklahoma being down for the last 4 of these 5 seasons. They only had to get up for a handful, at most, games per year.
And of course we know how openly they bent rules or outright cheated. Steroids, and who knows what else. Using players that would not be allowed in today's rules.
I highly doubt they survive these years so cleanly with a 4-team playoff of the top 4, at the end of each year, as well.