Some time ago I stumbled upon a fascinating website that let you change your scale, from the size of the observable universe down to the Planck length, showing objects of each size as you went up or down. It was absolutely amazing, the exact kind of thing I would love to have created myself, and I meant to share it but lost the address. Thankfully, I stumbled upon it again by chance recently, and get to share it with you now.
Here's the link: The Scale of the Universe 2. Go check it out!
Edit (5/14/2013): It might help if I actually had the right link! Fixed now.