A search on the Internet for resources for teaching statistics yields multiple sites with data sets, projects, worksheets, applets, and software. Often these are made available without information on how they might benefit learning. This paper addresses potential benefits from resources that target trend and variability relationships in bivariate data. The paper is in five parts. The first is the introduction. In the second, trend and variability are defined. In the third, the author quotes research on the characteristics of data that influence students' discernment of trend and variability, and identifies data sets that have particular characteristics and that can be freely downloaded from the web. The fourth part of the paper is a short review of free text-based resources. The final part is a review of spreadsheet programs and Java applets. The paper is relevant to teaching and learning in secondary schools. (Contains 5 tables and 5 figures.)