A Qualtrics script. Use at your own risk - I won't provide support for this. This is a V1 copy of a script that eventually went to V2 as a separate script, and became abandonware when I stopped working on surveys on mTurk.
However, the smaller feature set of V2 is a bit more user-friendly, since it was designed to work with more than just "matrix bubbles". Although incomplete, it was designed with end users in mind rather than just as a personal time-saver:
V2 has its own glaring flaws though, most notably that it consumes and reinterprets all keyboard events, so that even Ctrl+C doesn't actually do anything. In its unfinished state, it also can break some surveys, since (fairly rare) pages can break due to the lack of some yet-to-be-implemented features.
Both tools are incomplete, but if you're planning on using either of these tools, I recommend V2 -- especially because the infrastructure is set in place so that it's easily extensible (it correctly identifies and encapsulates all of the most common survey input types).