This userscript does multiple things to enhance the usefulness of individual requester results pages on MTurk. See screenshots below.
The easiest-to-explain thing it does is, it adds a complete 'Contact Requester' link and a 'TO Reviews' link to all requester results pages, even ones with no results found. When a requester doesn't have any HITs currently available, normally you'd have to go manually construct a contact link and manually search on Turkopticon if desired.
The search interface MTurk provides allows you to filter 'All HITs' with a basic keyword search, a minimum price, whether to only show HITs you qualify for, and whether to only show HITs that require Masters. This script extends that filtration capability to individual requester results, using 'hidden' functionality that's been available in MTurk's programming for a long time, but until now the only way to access it was by manually editing the URL. When viewing a requester results page, such as CrowdSource's for example, an area with an extra button will appear below the standard search bar to let you run a search using those filters within only that one requester's results.
Next to the 'Apply Filters To Requester' button is a text box for the requester name to be added to the URL in a 'prevRequester' value. As seen in CH MTurk Page Titles, this keeps track of who the requester was if you refresh the page to find no more results available, which otherwise would mean the requester's name wasn't there to be seen anymore. This name is automatically pre-filled in the box when you load a requester page that does have results; then, even when you don't want to apply filters to the results, you can quickly click the Apply button to just add that name as 'prevRequester'.
There's also a 'Re-sort' checkbox for if you want to add a hardcoded sort preference to that search URL, instead of having it display in whichever order you last chose on the main 'All HITs' pages; it uses your choice from the built-in 'sort type' drop-down selector on requester pages that currently have results, and adds its own replacement 'sort type' selector on pages with no results.
The resulting applied filter settings are displayed on the requester page, with or without current results.
MTurk's search results pages URLs are a mishmash of inconsistent programming. The first page of results for any kind of search you do will use one kind of URL query string format (the stuff after the question mark), and subsequent pages of results (page 2, page 3, etc) switch to a very different format, and there seems to be no way to retrieve later pages of results while using the first format. The first URL format is nice and readable and editable; the second 'viewsearchbar'/'searchSpec' format is obfuscated/unreadable to the point where very little can be done with it and very little information can be extracted back out of it. This meant that after building a custom-filtered URL on the first page of a requester's results, this script couldn't continue to display its filter settings on subsequent pages, although they would still be in effect. So to work around that, it adds the readable filter query values onto the URLs used in the links to later pages of results, so they'll be there to get information from even though they don't actually affect the current results if you were to manually change them at that point. (Applying changed filters using the interface would put you on a fresh first page of results with the new settings.)
Normally if you change the 'sort type' using the drop-down selector and click its 'Go' button, you end up on a re-sorted results page that's already in the icky unreadable URL format even on its first page. But this is unnecessary, since the sort type setting is also effective when included as a parameter in the readable URL format, so this script also overrides the 'sort type' Go button's action to have it stay with the readable format for the re-sorted first page instead.