From any source, what are the most intersting ideas that you have read or seen in Sci-Fi? Of course, not to give away the plot for those who may see or read what is referenced. I just saw one that was cool on Gattica [spelling?]. Genetically engineered piano players have 12 fingers. Music is written that can only by played as such. One of my favorites of all time [one of my first Sci-Fi novels] was by Clark. Here I first encountered the notion of violating causality. I had never really considered such an idea. For those who have read this, I refer to the invaders who looked just like Satan; unltimately associated with the end of the world. This is why we have always had the Satanic image in folklore. Of course, some of you may recognize a certain tourist planet that was eroding away due to the excessive amount of mass being removed by visitors. It is therefore required that you excrete as much as you eat - you get a receipt from the toilet - or the difference is surgically removed before you can leave for home.