There are many, maybe countless.  But, I found it interesting to look at two basic ones, and their combination.
Initial ground rule: I only worked with the current Week 14 AP Rankings list.  I didn't mess with who should or should not be in there at the bottom.

First, I looked at a pure RESULTS method with a simple sort.  The rules here are:
  1) A game played is of more value than a game not played.
  2) A win is worth 1 point
  3) A loss is worth -2 points
This is certainly most favorable to BYU, as it sits them at #2.

Second, I ventured a go at a PERCEIVED STRENGTH method.  By this I mean who I guess Vegas would pick as the winner in a head-to-head match-up at a neutral site with no fans - flat out, who they think is the better team in the match-up. Take 1v2 - who's favored?  Take 2v3 - who's favored?  etcetera.  I didn't go into any more complexity than that (but, but, but - A beat B, B beat C, but C beat A, so therefore...).  Just took a go at it.  I imagine there will be massive differences of opinion here.  I claim no experience or insight with betting, wagering, or anything of the sort.  It's just my best guess by impression.  It's obviously biased toward P5, 'cause that's reality.

Third, I just averaged the two ranks together for a COMBINED result.  Rather interesting, as it comes pretty darn close to the current AP poll, minus just a couple big anomalies (>= 5 diff from AP).
What are your thoughts?  Your rankings philosophy?