In cloud computing, you rent a server (or as many as you need) from a company like Amazon or GoGrid.com. You then load your software and data files on it, fire up the model, and log in later when it's done. The costs are very reasonable (~ $5 per day).
I have tested this on GoGrid.com and have a draft tutorial on how it works. There will also be a new version of parallel pest to work with this, along with other auxiliary software to make it all work better. If you are interested in the tutorial document, just send me an email.