Wikipedia:Tip of the day/February 14, 2008
Search for the category on that subject, by entering "Category:subject" (where "subject" is the category you want to see) into Wikipedia's search box.
To see if Wikipedia has any lists on the subject, type "list" and your subject into the search box, or check the List of basic topic lists and the List of topic lists.
Another useful link is related changes, which is a list of changes made recently to pages linked from a specified page. A good way to use that is to go to the main article for your topic (e.g., Biology, Music, Africa, Criminology, etc.) and see the related changes. Some unusual or obscure topics that you wouldn't have seen otherwise may surface.
What links here is also useful. Again, you should go to the topic's main article and see what links to it for an overview of related topics.
You can also look at the categories that the thing you're viewing belong to (at the bottom).