The tainted reaver: another fun little template! These creatures arise from someone being mentally scarred by taint (rather than physically, which produces tainted minions instead).
I'll be blunt: tainted reavers get essentially three abilities, and that's it. Fortunately, these are all quite interesting.
First is fast healing. Not dying is good, free out-of-combat healing is good, nothing else to be said here.
Then there's Madness (not entirely unexpected), which does what you'd expect. +6 charisma, -6 wisdom, immunity to Insanity and Confusion, and the ability to base Will saves on charisma rather than wisdom. The immunity won't come into play very often unless you face lots of enchanters, but the remainder of the feature is a huge advantage to anyone not reliant on wisdom.
Finally, there's Perpetual Rage, which grants a tainted reaver all of the default adjustments from a barbarian's rage (+4 strength, +4 constitution, -2 AC, +2 Will) without the restrictions that are normally imposed on his actions. This means they can still cast spells, make UMD or knowledge checks, activate magic items and anything else normally not associated with screaming frenzy.
This template is useful for a diverse group of classes: melee brutes benefit from the Rage, fast healing and higher Will saves, charisma-based casters will love their increased SADness, and higher survivability, and charisma-based gishes get considerable bonuses to their attacking and casting stat.
I tend towards +2 once more, but will assign +1 for now and let the community debate it.