I used a great little kit that came with all different coloured beads in cute little vials. It also came with glue which I didn't actually end up using.
I started by painting quite thick layer of nail polish on just one nail before quickly poured the beads over. To get a nice shape I pushed some of the beads around the edges back into place while the polish was still wet. Once it was dry I finished with a coat of clear nail polish to hold the beads in place and painted the rest of my nails. VOILA!
I did all this over a creased piece of paper which caught all the stray beads which I poured back into the vial once done.
Feast your eyes...