Ive noticed a trend in that the majority of bands covering Ghostbusters are Ska type bands. Attaboy Skip, Distorted Penguins, Lax Alex Contrax, and even Rasmus gives off a Ska sound, Coincindence? I think Not. Its cool though, It definately sounds good in this type. I also really like the Xentrix version as well.

I haven't heard these yet. Where can I find em?

I think it's mainly because if you follow punk and ska, covers are frequent and popular (and not to mention some of the best ways that bands hit the scene).