Fallout, Fallout 2, Fallout Tactics
First Aid, Doctor, Speech, and Barter get a +15% bonus. You get a -10% modifier to starting combat skills (Small Guns, Big Guns, Energy Weapons, Unarmed, Melee Weapons, and Throwing). This is a one-time bonus only.
This trait is useful, as it is unlikely for even a combat-oriented character to use more than 3 of these skills, and in all likelihood only 2. As such, 20% is "lost" while at least 45% (Speech, Barter, and Doctor) is gained. In Fallout 2, first aid is mostly useless as one can wait indefinitely. This is not the case in Fallout, as all 60% of this is useful. One may also tag their most used combat skills, negating the initial loss and increasing by 5%.
Fallout: New Vegas
This trait boosts all social and utility skills (Barter, Medicine, Repair, Science, and Speech) while lowering all weapons skills (Energy Weapons, Explosives, Guns, Melee Weapons, and Unarmed) by 5 points.
As with previous games, tagging a weapon skill during character creation largely negates any negative gained.