Xmonad is my window manager. I’ve had it configured to use dmenu as an ersatz command-line, but have been fairly unimpressed by its slowness, and by the difficulty of getting any notification of errors.
So I’m turning to yeahconsole. This is a drop-down terminal, something similar to yakuake, and hearking back ultimately to the headsup terminal in quake. To use: Ctrl-Alt-y to bring it up, type/run your command, M-A-y again to hide it.
I leave outstanding two jobs, one easy and one hard. Easy one is integrating it with xmonad, to launch on M-p. Hard one is making it vanish after executing a command; from a glance at the docs it seems this will only be possible by futzing with the source directly