I wrote a wrapper for Oracle's sqlplus CLI that uses the Readline library. I was influenced by the excellent Sqsh interface for Sybase (and MS SQL). OSqsh (which I'm pronouncing "Oh-skwish") doesn't really do anything extra so far, except that it makes the command history available using arrow keys thanks to the GNU Readline library. That alone is pretty much the whole point of OSqsh.
A while back, someone put a tip on the Gentoo forums for making Firefox store its cache in RAM rather than on the disk. It's a hack that basically mounts a ramdisk where Firefox stores the user profile. I haven't seen any benchmarks, but it seems like a good idea and I find the performance pretty good. This is especially appealing for netbooks that use flash storage instead of a hard disk.