Pocket Rosary Rings also known as Finger Rosaries are really good for your pocket or purse or to just tuck into your desk drawer at work so it's always within reach. They also make wonderful small gifts or tokens of thoughtfulness for friends and loved ones.
The Knights of Columbus has published a nice guide showing how to use a pocket Rosary Ring for prayer and meditation. You can download it here in .pdf format for printing:
Printable Card on How to Pray with a Rosary Ring
And here are links to the rosary rings available at Rugged Rosaries: