Ones that I thought could work.
Mafia Team Variant Roles - "Silencer", "Yakuza", etc.
The "Silencer" can 'silence' anyone each day (except whoever was silenced yesterday). The silenced individual wakes in the morning and is immediately instructed not to talk until the end of the day (They may vote and be executed though). The Silencer does not participate in the mafia killing, and the mafia do not know who their silencer is, but he is typically aligned with them and knows their identities. The Yakuza is a regular mafia player with an extra power: they may sacrifice themselves from the second night (during the night) and choose an innocent to join the mafia team.
Handicapped roles - "Murr", "Village Drunk", etc.
This role is, much as the power roles, taken in addition to the assigned role. However, it has the opposite effect, giving the bearer a handicap, like speaking only gibberish in the case of the Village Drunk, etc.
Recruitment Roles - "Godfather", "Psychiatrist", "Cult Leader and Followers", etc.
Cult Leaders recruit at night instead of kill; they act as an independent faction, usually with the ability to talk at night. The Mafia Godfather may be able to recruit innocent players into his faction under certain circumstances.
Special roles - "Baker", "Village Idiot", "Cobbler", "Doublevoter", "Priest", "Lawyer", "Survivor", etc.
The baker is on the side of the innocents. During the night, the baker chooses one player to be the recipient of a loaf of bread. If the baker dies, the innocents have just three nights to dispose of the mafia, or the innocents starve, and the mafia win. The Cobbler, "Village Idiot", or Jester has the objective of convincing the town to kill him, or is required to vote in favor of all proposed lynchings. Also, in some games there are players who can change the vote count. Some players have 2 votes (Doublevoter); some players can only "hammer" vote, or vote the final vote to kill a player (Actor); cannot place the final vote (Priest); cannot vote to lynch (Voteless Innocent); or require one fewer vote to lynch (Hated Innocent). The lawyer has the ability to represent any person, the person is selected during the night. If that person would be voted guilty instead they are saved. The survivor is a neutral player, and wins when any other team or player wins. There are endless special roles, and many moderators make up their own roles for games.
I'll leave the role up to the men and women of the City of Old Mellon