This feat is gold. Seriously, open your copy of Dragon Magic and take a look.
Yes, it only requires 1d6 SA/SS and the Dragonblood Subtype. Yes, it gives you +1d6 damage on your SA/SS, makes it into a supernatural ability, and changes the damage to a given energy type.
Now, what makes this awesome is stuff like playing a Dragonwrought Kobold Rogue. Why?
1. There are dragons that deal force damage with their breath. Stabbing incorporeal beings, anyone?
2. There are dragons that deal negative levels. Have allies take Tomb-Tainted Soul. Act as a minor source of healing.
3. Ask your DM if stuff like Pyroclastic Dragon (Breath Weapon does two different energy types) would allow you to apply the feat twice. If your DM allows it, have fun.
Then of course, there is stuff like Empower Supernatural AbilitySneak Attack, and a couple other fun things.
Say, is there a way to turn a Supernatural Ability into a Spell-Like ability? Mortalbane Maximized Empowered Vilified Sneak Attacks would be loverly.
Base SA: 10d6 (let's leave it here for the moment, OK?)
After all that (theoretical) crap: 100.75 Damage, half of that Vile.
So, in other words, I hope there's a way to make Supernatural abilities into Spell-Like abilities.