Wikipedia:Wiki2VCS, script that loads histories onto one's computer, so that they can be quickly diffed and searched
XTools Page History Page statistics and visualization, provides sortable and exportable list of all contributors with number of edits and amount of added text. Provides also results of syntax and grammar checks and latest assessment history.
Finding the responsible user
WikiBlame, searches for given text in versions of article
whoCOLOR, browser script for Grease/Tampermonkey, highlights original authors directly in the article, gets data from a publicly accessible API
Editor Interaction Analyzer compares the edits of two to three specified editors to see which articles overlap, sorted by minimum time between edits by both users. Only works on the English Wikipedia. Speed: slow.
Intersect Contribs, compares the edits of two to eight editors at any WMF wiki to see which articles overlap. Speed: fast.
MediaWiki Table Utility or this updated version This class constructs a MediaWiki-format table from an Excel/GoogleDoc copy&paste. It provides a variety of methods to modify the style. It defaults to a Wikipedia styling with first column header.
csv2other: a free open source tool, in .net, to convert CSV and EXCEL files to wiki table format
Mediawiki CSV Import tool: A proprietary, commercial, tool to create mass Mediawiki pages using CSV datasource and variable based templates. Results merged into a valid Mediawiki XML Import file.
wiki2csv: a commmand line tool that can convert wikitables to CSV and back. Useful to edit wikitables in Excel (or OpenOffice).
LibreOffice Writer is free. It can open almost any file format. It can export to Mediawiki: File menu > export > save as type > MediaWiki. It will save the file as a .txt file which can be opened with any text editor. Copy the wiki code from the text file. You can save any web page as an HTML file, and then open it in LibreOffice Writer. Edit as needed. Remove the parts you don't want. Keep only tables for example. Then export to MediaWiki. Tables can be further edited in LibreOffice Calc. See: Commons:Convert tables and charts to wiki code or image files. And: Help:Table and the section on spreadsheets and the Visual Editor.
Html2Wiki is an extension for MediaWiki that imports HTML
mw:Alternative parsers, programs and projects to translate MediaWiki's text markup syntax into something else, such as HTML
wikitable2csv is a web tool that extracts wikitables from a given page and converts them to CSV.
wiki2csv is a command line tool that can convert wikitables into comma separated value files that can be edited by Excel or LibreOffice. The result can be converted back retaining most of the original formatting.