Well, I'm getting a group together to playtest some of this content, but they want to try my Advances and Races. Problem is, he picked a Race I hadn't done advances for yet...
So here's a batch - the Tiefling and Aasimar Races, and the Assassin Class.
Fiendish Resistance - you gain Resistance (3) to one of Fire, Cold, or Electricity damage.
Prehensile Tail - you gain the ability to use your tail as an extra limb, capable of holding (and attacking) with a light weapon, or holding your weight for a number of rounds equal to your Strength bonus.
Demonic Negotiator - you gain a +2 bonus to your Communication skill when communicating with Evil creatures and characters.
Darkness - you gain Darkness as Spell-like Ability, a number of times per day equal to your Mind or Charisma bonus (whichever is higher). If you have already gained Darkness as a Spell-Like Ability, the GM may allow you to choose another from the Tiefling Ability Table, or a suitable spell from another source.
Devil-skin - you gain a +1 Natural Armour Bonus.
Celestial Resistance - you gain Resistance (3) to one of Cold, Electricity, or Acid damage.
Winged - you possess a small pair of wings, that can be used to glide for a number of rounds equal to your Strength bonus.
Angeltongue - you gain a +2 bonus to Communication when talking to Good creatures and characters.
Light - you gain Daylight as a Spell-like Ability, a number of times per day equal to your Mind or Charisma Bonus (whichever is higher).
Blessed - you gain a single re-roll per session, to any one roll.
Shadow Master - you gain a +2 bonus to your Subterfuge skill when hiding in shadows or darkness.
Dark-Adapted - you gain darkvision (or, if you already had it, the range of your darkvision doubles).
Well-Trained Nose - you gain Detect Poison as an at-will ability, with no HP cost.
Master of Disguise - you gain a +2 bonus to rolls to disguise yourself.
The Subtle Knife - you gain a +1 to-hit with all daggers and short swords.