I think the "20th century" solution to letting many users in different locations run regexes would probably have been to write a cgi-bin script in Perl, and have users paste text into a box on an HTML form.
The results page generated by the script could have checkboxes to mark each suggestion as useful/not-useful/incorrect and a submit button, with this feedback saved in MySQL.
(I'm not sure whether this qualifies as "without ... services")
- regex rules are updated frequently (let's say weekly)
- the updates are available to hundreds if not thousands of users in different locations
- all of them have the latest ruleset
- all of them capable of sending feedback regarding how useful and correct the suggestions are
- said feedback is analyzed regularly and used to refine the ruleset