Me neither and I can't work without XMonad.Prompt, especially the Shell instance, for spawning executables. I don't remember Tuumo's ion in detail but the only other launcher that behaves similarly in a sane way is cwm's built-in menu. dmenu_run doesn't work the right way and is limited in what it launches or auto completes. Like ion there are also instances for ssh and man pages. When using the shell prompt the memory usage goes up by 1 or 2 megabytes but that's constant. Any time I try spectrwm or dwm I always come back to xmonad.