My huge purse is usually filled to the brim, and a lot of the time I have multiple bottles of nail polish. I don't know how to explain it; I just love to paint my nails anytime anywhere. They always clink around together and I'm constantly worried that they'll break (one already has) and ruin the entirety of my bag.
The polish is actually of top quality. It applies smoothly without streaks and dries quickly. Exactly what you need when you're polishing on the go.
To use them, you just click the end of the stick (as if it were a pen), and carry on painting. One click is enough to do at least three nails. Be sure to clean off the brush at some point though. Since it's not going into a bottle of polish, these brushes can dry out fairly easily.
There are oodles of colors and each stick goes for about $7.