GraphChi uses a Parallel Sliding Windows method which can: process a graph with mutable edge values efficiently from disk, with only a small number of non-sequential disk accesses, while supporting the asynchronous model of computation.
The result is graphs with billions of edges can be processed on just a single machine. It uses a vertex-centric computation model similar to Pregel, which supports iterative algorithims as apposed to the batch style of MapReduce. Streaming graph updates are supported.
About GraphChi, Carlos Guestrin, codirector of Carnegie Mellon's Select Lab, says:
A Mac Mini running GraphChi can analyze Twitter's social graph from 2010—which contains 40 million users and 1.2 billion connections—in 59 minutes. "The previous published result on this problem took 400 minutes using a cluster of about 1,000 computers