The data catalog is the home of Splitgraph repositories on the web. You can add your own data anytime, or find public repositories on splitgraph.com/your company's own deployment.
Searching the catalog yields publically-available datasets. To refine your search, filtering on topics can be a helpful way to narrow results down.
Because Splitgraph has been built with Postgres in mind, if your app already uses PostgreSQL, it may be particularly useful to unify disparate data sources into one path.
Open Government Data
If your app needs open government data, consider the Socrata catalog, which indexes upstream Socrata datasets nightly.
The Open Data Monitor is an example app that scrapes this Socrata catalog for diffs.