Search the online database for the abstract of articles on the topic dear to your heart. Follow up with a trip to the library if the article looks interesting and not too technical. Some articles will be understandable with high-school math, some others require more background. Mathematics Teacher is aimed at high-school math teachers, but lots of their articles could form the basis of good student projects. This also has an online database.
Selected articles are available online.
An on-line version of a magazine for students called Math Horizons. Another index for College Mathematics Journal and the Two Year College Journal, by subject. Articles on probability and statistics, with discussion questions to stimulate further investigation. Lets hope parties can come to some agreement so this great resourse becomes available again.