Journal of Statistics Education Data Archive Datasets contributed by statistics teachers. Raw data are in a .dat file with explanations a .doc file. Many of these datasets are tied to longer JSE articles discussing their use in statistics classes.
Statlib Dataset Archive One of the original (and still best) sources for archived data.
CHANCE Project Datasets Data from recent media coverage of current events. Only a few datasets here, but many excellent references to teaching applications of statistics in the news can be found at the main CHANCE page.
SICL - Statistics Instructional Computing Laboratory Datasets sponsored by the Statistics Dept. at N.C. State.
Worksheet Files collected by Dennis Roberts at Penn State.
Datasets in Excel, NCSS, or tab-delimited ASCII, with suggestions for appropriate statistical topics - part of an excellent set of resources for Exploring Data produced Rex Boggs.