Very few feats published in official supplements or Dragon touch lay on hands:
Action Healing (Faiths of Eberron): spend an action point to lay on hands with 50% extra healing, lay on hands as a swift action, or lay on hands from up to 30 feet away. Even if we assume you’re using action points, action points are way more valuable than those effects.
Azure Touch (Magic of Incarnum): Grants 1 point of essentia, and allows you to basically trade away essentia for the day to gain another use of lay on hands (or wholeness of body). Essentia is way more limited and valuable than uses of lay on hands, so that’s a pretty terrible trade—the bonus point of essentia is by far the more valuable thing from this feat.
Serenity (Dragon Compendium): Use Wisdom instead of Charisma for all paladin abilities, lay on hands included. Fantastic feat, but because of divine grace, not because of lay on hands.
Touch of Silver (Faiths of Eberron): Burn a use of turn undead to make lay on hands hurt lycanthropes and evil outsiders as if they were undead. Which is, again, a terrible trade.
In three out of four cases, these feats involve trading away some limited resource in order to get some minor effect: these are terrible feats. Serenity is good, but not particularly because of lay on hands.
Which kind of works out, because lay on hands is a very weak ability. It is a really bad idea to invest feats, which are very scarce and extremely valuable, into it.
I do not know of any third-party feats that significantly change this conclusion, but I am also generally unfamiliar with third-party material.