Skill Focus( Player's Handbook v.3.5, p. 100)
Choose a skill, such as Move Silently. You have a special knack with that skill.
Enhance Effect (PG) , Keen-Eared Scout (PH2) ,
You get a +3 bonus on all checks involving that skill.
You can gain this feat multiple times. Its effects do not stack. Each time you take the feat, it applies to a new skill.