I've been poking around the TNT website, watching bits and pieces of old S1 episodes and something came to me.
In "Salvation," the show seemed to suggest that the kids that were chosen to be Azazel's "special children" already had some specialness to them. The mother of that little baby girl said something to the effect that sometimes she felt like the girl was reading her mind.
That's never really been addressed since, but I know that people speculated that kids like Sam already had some predisposition to being special before Azazel messed with them.
Could it be because of his "special" bloodline? Sam and Dean come from a bloodline where they can become angel vessels. Could old Yellow Eyes have been picking families that had a certain bloodline? We know the moms made deals and that is why he came to the babies ten years later. But it was just a thought I had.
On a random note, I love some of the lines dropped in the early seasons that have so much more meaning now:
Azazel to Dean: What are you and God gonna do?
Doctor to Dean (paraphrased): You must have an angel over your shoulder.
I also noticed that the online episodes have different music. I assume they had some rights disputes for either online or syndication? Some of the classic rock has either been changed or dropped. That's a bummer.