Variety Night-mare!

As my very first production for a very long time, I'm producing/directing a Variety Night in my little country seaside town....I've had some fantastic help from the wonderful people here before, and now I need to ask for help again! With less than a week to go, I have had 3 acts and the MC pull out! Talk about a NIGHTMARE- I have managed to fill in a spot, but I am stuck for a song we can use for a Finale to make up for the shorter program- we are looking for something simple, yet with a heap of WOW factor! We have the most fantastic male and female singer, who will lead the singing..... Also, is there somewhere I can go to find a pre-written/easily adaptable script for an MC? Thank you again, for ANY help you care to send our way! email- tumbybaydramaclub@yahoo.com