Ok now head up to DragonFlyBSD and check their latest 2.0 release. Now there's something new to look upon. The DragonFlyBSD team has created a new filesystem named HAMMER (pdf file). From what I read, the filesystem is an innovative new filesystem fer DragonFlyBSD and the developer has stated that they're commited to make the new filesystem as widely accepted by other *BSD siblings and other OSes.
Go and check that out.