I came across this closing screen of an ancient King Kong movie (via FFFound).

1. Vintage closing screens actually make a nice final slide of a presentation, you Google lots of them
2. Always close your presentation with a sentence that makes it clear that the presentation comes to an end. "End that is how....". Don't say explicitly "well, this is the end". Let questions come up spontaneously, and don't say: "OK, I have time for 5 questions", there just might be chance that no questions will come up (a bit awkward). I have seen many great presentations without questions.