Catching up on my backlog of periodicals, I read with interest, "Outperforming LRU with an Adaptive Replacement Cache Algorithm" (Computer, Apr 2004).

• Link: IBM research page to the authors' papers regarding this LRU/LFU hybrid.
• IBM's pending patent application: 20040098541.

Hmm... I see (or more accurately, searched and found) PostgreSQL and Jakarta Turbine JCS developers already implemented ARC variants/derivatives for their respective code streams.