The ability of stabbing someone in a vital organ when they aren't looking. Ability increases in power by the level of the character. For full details, see the player's handbook.
A backstab with a missile weapon. Has the same requirements as backstab (including the target being unaware of the attacker). Note that the attacker may be able to snipe multiple times, by sneaking away and firing from a different spot.
How to speak the lingo, walk the walk and talk the talk. The ability to speak the secret "tongue" of the thieves. Often a requirement to be accepted as a true rogue in various shady guilds.
The traditional bardic skill of making people feel sad, or happy, or lonely. Modifies reactions by one step if the character has a chance to perform first. A character without this skill can never be an "entertainer", although they may be renowed for their (say) singing skill. This skill applies to any kind of performance, so any kind of performing entertainer could take it.
The character receives a saving throw bonus against the listed attack form.
"Music has charms to soothe the savage beast". A meistersinger skill, this calms animals and makes them more likely to be friendly.
The use of the skill will prevent any sound based attack from occuring within 30 feet, while the character creates noise. No other action is possible while performing this.
The character has heard of many legends, granting a 5% chance per level of hearing of legends of particular items. The information granted by such is up to the DM (although see the players handbook and bards handbook for details). The character also gains the local history proficiency. A skill useful for a bookworm as well.
This ability grants a pleasant sounding voice. A character without this skill will never be able to perform on the merits of theirkill alone (although if they are quite entertaining, they will do well in taverns and the like). This also grants the singing trait and the instrument trait. (+2 to singing score, and 2 CPs in the musical instrument skill for every CP spent). (Think of Pavaroti compared to your local pub's band. Both may have practiced a great deal, but one has the talent, and the other doesn't).
Inspiring groups. See players handbook for exact details of effects.
A knowledge of basic linguistics, and a smattering of languages. The character Has a chance of understanding any written material. Spoken material is generally too fast for the character to understand it.
The art of deciperhering the magic runes to use a written magical item. This differs from the mage scroll use in that the character need not be a mage, and any written magical item may be used, even one destined for another class.