So, this is something I noticed years ago and I'm not sure if it has been mentioned here before, if so I apologise I am new to this. However, I was reading the Chamber of Secrets again and came across this passage during Harry fight with the basilisk.

"Help me, help me" Harry muttered wildly , "someone, anyone!" The snakes tail whipped across the floor again. Harry ducked. Something soft hit his face. The basilisk had swept the Sorting Hat into Harry's arms.

Now at first this seems like a coincidence. Because Harry is one of the luckiest people alive. However, when you consider the latter half of the books it begin to make a lot more sense. What if Harry in his panic, had been calling out in Parseltongue and the basilisk, who only obeyed Voldemort. Actually listened, due to the part of his soul within Harry. Therefore, when he called out, the Basilisk had no choice but to help him.

Thus giving us one more easter egg, well before any of the books were coming out. This seems especially more likely considering it was the introduction of the first Horcrux.

Like I said, I'm not sure if this is an original idea, of if anybody else has noticed it before. It is just something that has always struck me as odd and when I read it again this time, I decided to see if anybody else had noticed this.