It allows you to effect 1 extra target per level with a spell that has a single target. All targets have to be within 30 feet of each other. The level adjustment is 3 levels I think.
I don't know of any metamagic feats that turn a targeted spell into a burst effect (you mean like magic missile going KABOOM?) but I do know of a spell that has an effect like that.
It's one of the Nectrotic spells from Libris Mortis. If the target makes his save he gets d6/level damage, max 15d6. If he fails he dies and everyone within 20feet takes d6/level damage, max 15d6. And half the damage is vile .
I seem to recall having read something like recent inone of the freely available netbooks - Netbook of Feats or Gryphon's 3ed Feats. try those. Sorry I don't have a link for you.
It allows you to effect 1 extra target per level with a spell that has a single target. All targets have to be within 30 feet of each other. The level adjustment is 3 levels I think.