Just want to throw in Luthien Tinuviel into the ring. She basically did everything Orpheus did (oh, and she succeeded), pleaded with and put to sleep the maybe mightiest god-like power in her world and also befriended a giant hound which became so loyal he helped her defeat Sauron. If you'd ask me of a picture of a really powerful, epic solo bard, Luthien is your woman.
But I agree that bards and the usual bardic way of solving problems (at least how it is depicted in fiction) doesn't work too well in your standard D&D troupe where social encounters only happen with people who are at least indifferent towards you. However, if your group agrees on using violence only as the second-best answer to running an encounter, then having a bard around is pure gold.