The Raspberry Pi's great, but it's certainly not that powerful. One way to boost that power is to create a cluster computer. Instructables user gigafide shows you how.
Clustering together a bunch of Raspberry Pi's isn't exactly a cheap option, but it can still be useful if you just need a bit of a boost for some Raspberry Pi's you already have sitting around. You'll need at least two Raspberry Pi's for this, but you can use as many as you want.
After getting the basics set up on each Pi, you'll link them together with a couple of commands and end up with a more powerful cluster computer. It's not exactly going to blow a modern computer out of the water with its performance, but it might provide the extra boost you need to finish off a project of your own.
How to Make a Raspberry Pi SuperComputer [Instructables]