No, but bardic knowledge gives you a class bonus to all of your knowledge skills whether or not you have any skill ranks in it! And knowledge skills can be incredibly useful, especially for a bard, don't discount them just because you don't get all of them... Think about which things your character would already know the most about and put a rank in each, thanks to the +3 for being a class skill that's really all you need in each for now.<br/><br/>Getting every knowledge skill in one would be very overpowered, and kind of not fair to everyone who only gets one or two even as class skills...