Your body is doing Mitosis right now. Mitosis is how cells divide to make new cells and copy their DNA and all. You started from one cell (with half the DNA from sperm, half from egg) and that cell multiplied billions of times to make you. Cells are being replaced all the time too.
These images are taken using Fluorescence Microscopy. I copied them from the University of Florida Molecular Expressions Gallery, which is one of my favorite sites on earth. The stuff they photograph is stunningly beautiful.