The scale of things small
Via metafilter, I find this: Cell size and scale, which is a neat little web app (flash, I’m guessing by the way it steals the mouse focus, though I haven’t checked). It allows you to zoom smoothly, viewing things as large as a coffee bean or as small as a carbon atom. The smooth zooming really gives you a much better feel for the relative sizes of things than similar things I’ve seen in the past which jump in 10x increments. One perceptive metafilter commenter asked how come it was that the X chromosome shown seemed too large to fit into the sperm cell which was also shown. Another few commenters clarified this mystery. Apparently there are special “packing” proteins in the sperm cell that kind of squash the chromosomes down. Neato.
Another metafilter commenter mentioned universcale which I’d seen before, but forgotten about. It i s kind of similar (though a bit more annoying with the music and intrusive interface, but still neat, and well worth checking out.)