Makes a *huge* difference in performance...
...of my installation scripts (reading tarballs off NFS, decompressing them and extracting the contents onto the hard drive -- added a buffer between all three steps, using pv to view where in the process each component is at). Dropped total runtime by more than 2x -- *much* more. Very good stuff.
(One thing I noticed -- the online usage text is more up-to-date than the man page, which missed some of the new features).
An open, cross-platform journaling program.
A scientific plotting package.