Oooooooh. Yeah! Then maybe add a dual exhaust. Cool..... The second one could be for the leftover electrons.
It doesn't look too bad. Just accents the stock exhaust. 2010-2011 Toyota Prius Polished Exhaust Muffler Tip: eBay Motors (item 220605015436 end time Jun-11-10 17:57:15 PDT)
The stock exhaust pipe end is curved down a little so the chrome tip my not look quite like the one in the picture when it's installed.
You could do a custom duel exhaust like this: PriusChat Forums - strieby's Album: 2008 Prius Photos - Picture
It does look neat, but I don't want to use a recording of my other car to back up those tips. It just seems silly with our car. But, to each his own. Does look good.
I just picked one up from Pep Boys which I think is made by 3A racing. It's not too big and flashy so it looks stock. They simply screw on to the exhaust pipe. I believe there are three screws. Simply leave one out to straighten it onto the downwards exhaust pipe.