Maybe someone should pull LMDB's mmap/paging system into a usable library. I'd love to use the k/v store part of course, but I keep hitting the default key size limitation and would prefer not to link statically.
It wouldn't be much use without the B+tree as well; it's the B+tree's cache friendliness that allows applications to run so efficiently without the OS knowing any specifics of the app's usage patterns.