Using EBS has lots of advantages--reliability, snapshotting, resizing--but overcoming the performance problems by using Provisioned IOPS is expensive.
Swrve, an integrated marketing and A/B testing and optimization platform for mobile apps, did something clever. They are using the c3.xlarge EC2 instances, that have two 40GB SSD devices per instance, as a cache.
They found through testing RAID-0 striping using a 4-way stripe along with enhanceio, effectively increased throughput by over 50%, for free. With no filesystem corruption problems.
How is it free? "We were planning on upgrading to the C3 class of instance anyway, and sticking with EBS as the backing store. Once you’re using an instance which has SSD ephemeral storage, there are no additional fees to use that hardware."
For great analysis, lots of juicy details, graphs, and configuration commands, please take a look at How we increased our EC2 event throughput by 50%, for free.