Primecoin Mining is still mainly done on CPUs, with the ongoing spikes in interest regarding XPM it is now profitable to rent servers for pennies on the hour and put them to work mining XPM. Renting cloud services to mine is a great way to decentralize the mining network and add security to the network, as well as make some money on the side. I am going to show you how.
What you will need:
Paypal account or valid Credit Card.
Primecoin (XPM) Address [from your personal primecoin client or from your preferred cryptocoin exchange]
Internet connection
Read more here:
http://www.cryptocoinsnews.com/2013/12/04/primecoin-cloud-mining-using-digital-ocean-complete-guide/