Helping fill the void between expensive, large capacity SSDs and slow, but cheap high capacity mechanical drives, OCZ has just outed a new range of cache happy SSDs it calls the Synapse Cache. The new series includes two capacity drives of 64 and 128GB, certainly more than enough for caching purposes.
The Synapse Cache drives include Dataplex cache software from NVELO which will dynamically cache the most recently, and frequently accessed files from your large capacity platter drive to the SSD; thus increasing overall performance in accessing those files thereon. It's essentially how Intel's Smart Response Technology works, but in this case it's all handled via the SSD combined with the Dataplex cache software as opposed to the motherboard chipset, meaning you are not limited to Z68 for this type of setup.
Touching base on the rest of the Synapse Cache specs, they are of course 2.5-inch sized drives using a SATA 6.0 Gbps interface with MLC NAND Flash memory and include TRIM support. The 128GB version is capable of read/write rates of up to 550/510MB/s while the 64GB delivers read/writes rates of up to 550/490MB/s.