Is there anything that allows you to attack Material targets while you are Ethereal?
?
I believe some creatures have special abilities that do, but all the text for the Ethereal plane indicates that the answer is no.
One might convince a GM that the Ectoplasmic Spell feat, since the flavor text talks about working across the dimensions, should work in both directions.
On the other hand, I suspect that the restriction is in place for a reason: since Ethereal creatures are pretty much undetectable yet can see the Material Plane, any such ability would be an "I win" combination for Ethereal creatures.
What you'd need would be something like the old Transdimensional Spell metamagic feat from 3.5e, but I'm hoping that such an animal never gets created for Pathfinder, as it has disturbing side-effects.
Like being able to drop fell drain thanatopic transdimensional magic missiles from the Ethereal plane. Ugly.