Much of my work on Wikipedia relates to geography and/or history.
Counties, townships and towns
Being a Hoosier, my focus was originally on Indiana towns, townships, and counties, but that has expanded to other parts of the nation. I created most of the Indiana township articles and produced a locator map for each, and produced the locators for townships in Illinois and other states as well. I am willing to create other such maps if the need arises; this can be often done on a semi-automated basis using custom-written scripts (which depend on PHP MapScript, part of the open-source MapServer system) and freely-available mapping data from the United States Census, the National Atlas, and other sources.
When it comes to small towns, old atlases and newspapers on microfilm are wonderful resources. It's interesting how people in the 1870s in the midwest used the same language we do now, naturally, and yet once in a while it's difficult to know what they were talking about when reading old newspaper articles; frames of reference have shifted over the years. Below are a few of the maps I've scanned from an 1877 atlas, which I find rather fascinating. These have also been set up with overlays for viewing in Google Earth, per Geocoding/Overlay, which lets you view old maps on top of current satellite images. A useful tool here was the Microsoft Research Image Composite Editor, a free tool which allowed me to scan quadrants of the atlas' large pages and then stitch them together to form single complete images; it's also great for making panoramic images out of sets of photographs.
In order to help provide better in-article descriptions of Indiana state roads, I have created many maps for those articles using MapScript. I also created a number of Indiana state road articles, ensuring that each road had an article, and added sourced milepost data to those and many existing articles.
Another goal is to provide at least one photograph of each of the towns and points of interest in Vermilion County, Illinois, for inclusion in the related articles. You can view my photographs on Wikimedia Commons.
Library in Ridge Farm, Illinois
Museum in Westville, Illinois
Grain elevator in Cheneyville, Illinois
Iron bridge near Armstrong, Illinois
Warren County, Indiana was the first United States county article to be promoted to Featured Article status, in February 2011, and it is still the only one.