Assuming that with those 12 fighter levels he's got all the feats he needs for his chain tripping schtick and more fighter levels are wasted...
Which other classes would be good to take? Barbarian for rage I guess. Would 3 levels of rogue be any good for a bit of sneak and maybe maxing some non-fighter skill? Or ranger for handle animal then train them for assists? Maybe get the wizard to feeblemind monsters and then train them...?
What would be decent skills for this char?
None of the core prestige classes look very good for this character.
I'm tempted to take ranger to have better options for skills: use rope, survival, handle animal, spot, ride, hide, move silently, intimidate, knowledge (dungeoneering). And for the archery path. But then I'm not sure if I want to either delay taking the chain tripping feats, or get the ranger skills/abilities very late in character development.
Fighter 10 / Ranger 10 looks good to me. Makes him a battlefield controller with some mediocre ranged fighting and some skills. Would this guy fit in a 4-PC standard party (tank, skill monkey, arcane caster, divine caster), in the role of tank?