I've always kind of liked the Vows from the Book of Exalted Deeds, though I understand that they are not great for optimization. I appreciate them for their RP value and their still nifty abilities. (I mean, come on, Vow of Peace IS a pain, but weapons shattering when they hit you? Awesome.) As I'm playing in a campaign where the DM has effectively done away with alignments, favoring the "shades of grey" mindset for morality, I wondered how that would affect something like the Vows. And I realized it would be pretty easy to make them more evil/selfish, or at least less "shiny, happy, rainbows out the ass" good. In fact, you could think of them as being more Lawful than Good. For example:
Vow of Obedience - Loyalty to an organization that is neutral or even evil
Vow of Poverty - Donate money to above organization or to some other "evil" organization (Who says orphans should get everything?)
Vow of Non-violence/Peace - Though it seems like it would have to be good, I could definitely picture a group of peaceful villains who "wage peace" and demand conformity, especially since they get bonuses to their non-lethal compulsion spells and the like. Think Clockwork Orange or Brave New World.
I'm passing on the Chastity, Purity, and Abstinence Vows, since they work off preconceived notions (sex is bad, drugs are bad, eating meat is bad, etc.) and I don't want to get into a moral argument.
Anyway, like I said, I feel like you could definitely create a non-good character using the Vows if you RP it well. The example I thought of was based off the Witch class. With her hexes and lack of blaster spells, she makes a good buff/de-buff/controller. Basically my idea is a witch who works for a shady organization as something of a bounty hunter; she goes out and "collects people" for the group. Due to trouble in her past that the group saved her from she has sworn a personal loyalty to the group (VoO) and wishes little more than room and board from them (VoP), though part of it has to do with how much she enjoys the job in her own way. And partially due to traumatic events in her early life, but also due to her job description, she avoids killing her targets or others who get in the way, unless it proves absolutely necessary (VoNV)
Again, I'm looking at this from a flavor/RP point of view, rather than building the "COOLEST WITCH EVARRR!!!1!", so I'm just curious what everyone thinks of my interpretations and the viability of the character. Please share any opinions, additions, criticisms, and the like.