The National Championship Foundation was founded by Mike Riter of Germantown, New York. They retroactively selected national championships by member vote for every season through 1980, then named national champions every year thereafter through the year 2000.
Although the National Championship Foundation is not generally seen as authoritative, they are, along with Helms and the College Football Researchers Association, a source for national championship selections prior to the AP poll's 1936 launch.
However, it is hard to trust the NCF's pre-1936 selections because some of their modern day choices are so obviously silly. Such as 1993, when they share the title amongst Florida State, Notre Dame, Auburn, and Nebraska. The first three make sense, but Nebraska lost to Florida State in the Orange Bowl, and has no argument at all for sharing the title.
Then there's 1981, when everyone picks Clemson except the NCF, who shares the title amongst five teams: Clemson, Pittsburgh, Nebraska, Southern Methodist, and Texas. Clemson was 12-0, and defeated 9-3 Nebraska in the Orange Bowl. I have no idea what the rationale is there. But there were apparently some Nebraska fans amongst the membership. Nebraska fans who had trouble accepting reality, no less.
Still, for all that, the NCF has its merits. They are often better than the AP poll (though the above choices are not at all examples of that). After all, they correctly tab Tennessee for 1950, when the AP's team, Oklahoma, lost their bowl game.
As you may have noticed, the NCF hands out a lot of ties, which I generally applaud (though not in the above examples). Their 1973 tie amongst Notre Dame, Ohio State, and Michigan makes perfect sense. They recognize Penn State along with Nebraska in 1994, when no one else does. It seems unfair and arbitrary that Michigan shares the 1997 title with Nebraska, but PSU '94 does not.