Here on Wiktionary, I mainly edit Ancient Greek entries. I have a decent grasp of Latin too, and some knowledge of Old English. I can read the Arabic alphabet and have a decent understanding of the morphology. I am quite fascinated by historical phonology and wish there were more phonological information in etymology sections on Wiktionary, to make it less of a mystery how words have changed form.
I have a good understanding of much of our module system, so I often fix bugs. I have files of entry names for each language and of instances of a fair number of templates from the dump, so I can quickly search templates and entry names by request.
I've created a number of functions using TemplateScript to perform tedious editing tasks with a single click, like adding {{non-gloss definition}} or {{subst:chars|grc}}, updating Ancient Greek conjugation tables, or converting lists of derived or related terms to the templates {{der3}} and {{rel3}}. These can be found here.
Other scripts:
contributionsTab.js: add a Contributions tab to pages in the User and User talk namespaces
cleanup.js: add buttons above the textbox to perform tedious editing tasks and add an edit summary
I wrote Rust programs available on GitHub, one with subcommands for quickly grabbing all instances of a set of templates from the dump and for generating information on headers used in entries (for the latter, see below), and the other for processing pages in the dump with a Lua script. Ask on my talk page if you want lists of particular templates, or all instances of a template that contain particular text.
I speak a weirdly simplified variety of American English with a split based on Canadian raising and no distinction between the "short i" vowel and schwa.
My brother and I created a 24-hour clock that shows the path of the sun on any day at any location around the world. See NaturalClock.net. (It needs a lot of work on its user experience.)