I'm using this 'clickhappier-archive' account to post archival copies of old MTurk-related userscripts from userscripts-mirror.org (which is itself an archive of the defunct site userscripts.org) and forum posts, which their authors or others haven't re-posted on Greasyfork yet. Some of these may no longer be all that interesting as more recent scripts may do what they do better, but some remain very useful.
Script Summary: Puts remaining time on mTurk hit into titlebar.
Version: 1 [03-15-2015 minor update by clickhappier to 1.0.1]
Note from Clickhappier: I personally consider this script to be essential. You can see how much time is remaining on a HIT in another tab by holding your mouse over the tab to reveal the full title in a tooltip. If you're also using CH MTurk Page Titles, you can either: - have this timer script run before the titles script in your Greasemonkey/Tampermonkey execution order if you want it to replace the titles that were generated by the titles script (as if the titles script weren't there at all on accepted HITs); - or have this timer script run after the titles script if you want the timer to be appended to the more-informative titles generated by the titles script instead (this is how I use it now).
This userscript can be even more helpful if you're also using a browser add-on/extension that allow you to see a list of your open tabs' titles, such as Tab Mix Plus for Firefox (enable its Opened Tabs toolbar button), and Quick Tab or Tabs Outliner for Chrome.