*Kasanegafuchi and Sarayashiki - not only are these the names of the two rival junior high schools, they are also the names of two famous Japanese haunted houses.
*Urameshi - a sound typically made by a wailing ghost. Whooo~.
*Kuwabara Kuwabara - a phrase typically said when anyone suspects a ghostly presence.
*Yuusuke - the "yuu" part of his name is the character for "ghost," just like the series. I think his name can be read as "ghost hunter," but don't quote me on that. I fail at reading Japanese, die.
*Atsuko - is most likely read as "hot woman." Again; I can't read Japanese. Die.
...I will add more later. Unless I forget. I'm sure this was all vaguely helpful.