My playground for working with articles about file formats on Wikipedia.
This script will output wikipedia articles that are in the Computer file formats category. If you pass it an integer it will descend that many levels into subcategories. The output for levels 0, 1 and 2 are available here as:
You'll notice that as you wander down in the category hierarchy below Computer file formats the articles become less and less about file formats. That's because the Wikipedia category system is a graph, not a tree, and it can wander about a fair bit.