I ordered these from eBay a while ago and have had plenty of time to try them out. I really like them because they give a much more precise dot than the sharpened pencil I was using before. Very cheap at £1.39 for five including P&P and the different sizes are good too, doesn't make that much of a difference though.
Thought I ought to post some photos showing what you can do with these. You don't have to just do dots though, you can use it for moving the polish around on the nail in to other patterns.