The CORGIS Dataset project is a collection of really great, interesting, and situated datasets. These datasets are explicitly constructed to be easy for introductory computing students to pick up and use. In our own experiences, we have used these datasets for both small practice programming problems, and for large-scale self-directed projects for students.
For a place to help out, check out our Issues.
For help on contributing new CORIGS datasets, check out contributor.md.
For help on extending the CORGIS infrastructure, check out extending.md.