My thoughts are a number of different tie breakers as in chess or MTG:
1) Strength of schedule
2) The result of the direct encounter(s) between the players (if any)
3) Greater number of wins
4) Just-Burg Scoring
To calculate this, sum the running score for each round. For example, if a player has (in order) a win, loss, win, draw, and a loss; his round-by-round score will be 1, 1, 2, 2½, 2½. The sum of these numbers is 9. This system places more weight on games won in the early rounds and the least weight on games won in the final rounds. The rationale for this system is that a player who scored well early in the tournament has most likely faced tougher opponents in later rounds and should therefore be favoured over a player who scored poorly in the start before subsequently scoring points against weaker opponents.
5) Sonneborn-Berger (linked before)
6) Greatest number of wins against a Wizard