Re: 8-fight streaks
Sergio Martinez - Barker and Macklin could be considered sub-world level
Chad Dawson - That's a great run of fights. However there are 3 rematches in there. I didn't clearly distinguish between 8 consecutive fights and 8 consecutive opponents, but I think that to fight 7 or 8 different guys in a row in 8 fights and have them all be world class is particularly impressive, because it speaks of a desire to step in the ring with anyone and the fighter has to deal with more diverse styles.
Winky Wright, Shane Mosley - yep, both arguably better than Froch's 8. I guess most of the examples are from modern fighters towards the end of their careers, because these guys only fight once or twice a year and therefore haven't got time to spare for fighting weaker opponents.