What makes a presentation memorable?
The secret is, the human mind loves stories. Your favourite conference talk was simply a very good story.
Stories are not limited to films or television shows. Every technical topic can be presented as a story. Yes, even explaining a linked list to beginners.
If you are looking for an in-depth guide to writing stories, I highly recommend Story by Robert McKee. Although it appears to be about screenwriting, the lessons apply to any kind of public speaking.