Thanks a lot guys! I really don't think there is any rhyme or reason to it. I'm still jealous of your guys' shots so I doubt it has to do so much with quality. I think, in terms of magazines, these guys are looking for pretty specific images, and if they don't have one they like with stock images, they begin searching. If they happen to come across one of our images, AND happen to like it, AND it fits their specifications, then they will pursue it. So basically, I really think it comes down to a lot of luck.
These guys contacted me through anet, and by personal experience I would say that 80% of the time I am contacted through anet or jpnet. The other 20% is through flickr (I've sold a weather photo to a Japanese magazine on there), facebook, or my website. Most of those are people looking for freebies and I send them on their way, but every once in a while it is a serious inquiry. This is why, I know I've talked with Steve about this before, I continue to upload to those sites despite some gripes about the upload/screening process here and there.