Repulsion's got a nice, 'this emits that, hits this; see Newton's third Law' explanation. Attraction. I found one thing. It says this: A virtual particle with momentum p corresponds to a plane wave filling all of space, with no definite position at all. It doesn't matter which way the momentum points; that just determines how the wavefronts are oriented. Since the wave is everywhere, the photon can be created by one particle and absorbed by the other, no matter where they are. If the momentum transferred by the wave points in the direction from the receiving particle to the emitting one, the effect is that of an attractive force. I guess the first question should be: is this accurate? I have others, but it would seem better to not voice them until someone can confirm, or put it in otherwords.