Allows locking your screen without hiding its contents (i.e. just disables input/interaction.) Nice for when you want to keep some stats, top, or just a plain message visible on your screen.
- sm
"screen message". Goes fullscreen and just gives you an editable text field to type a message into. Great to combine with xtrlock mentioned above to put something like "brb, grabbing coffee" on your screen for your colleagues or so :) (Technically a Gtk app I think, but fits the pattern.)
- [ed.] Xephyr
Open another X server as a window in your current X server. Great as a "canvas" for a screenshare if you want to share multiple windows but not your entire desktop. Batteries not included, you need to know how to juggle xauth & a WM (metacity for me) to make the new X server actually do something.