The Alt+<backspace> (kill last word) and Ctrl+W (kill last path component) family of keyboard shortcuts are very useful, particularly when editing previously issued commands, as they allow deleting chunks of command-line parameters faster than character-by-character. Beneath the hood, they are implementing using the forward/backward-kill-* functions, and in particular, *-kill-path-component. However, in many cases, it would be very convenient to have a keyboard shortcut for killing an entire argument. For example, given the following input with the cursor at the end:

$ mplayer --no-video music/a.mp3

pressing Ctrl+W here will delete a.mp3, but there is no shortcut for deleting the entire last argument (Alt+<backspace> would delete only mp3). This can in many cases be useful when you have a complicated command invocation where there's a a single (but potentially long) argument that you want to change.

I propose another variation of the -kill- commands should be added, namely forward-kill-arg and backward-kill-arg, that delete the next and previous argument respectively. In particular, in the above example, backward-kill-arg would kill the full music/a.mp3. I'm not sure what a good shortcut would be for this (nor whether one should necessarily be provided by default), but it certainly seems like a useful feature!