Petros Koutoupis is the developer of RapidDisk (also known as rxdsk) is designed for high-performance computing while being designed to be simple. RapidDisk can handle dynamically adding or removing RAM-based block devices of varying sizes, LZO data compression (still being implemented), and SHA-256-based error-correction.
RapidDisk is meant to be used for quick I/O storage (such as using a solid-state drive for the RapidDisk), application/database caching, file-system meta-data caching, virtualization, and as possible replacements to CompCache and CacheFS. RapidDisk volumes can also be easily exported as a physical device across a SAN or allocated as a SWAP space.
This kernel module isn't living in the mainline kernel tree (at least not for now), but is licensed under the GNU GPLv2 and its user-land utility goes for the GPLv3 license. More information on RapidDisk can be found from the 1.0 blog announcement and the project's Wiki.