First draft (in progress): Isabelle Guyon, Romain Egelé, Frank Hutter
Repositories (contain many tabular dataset, but also include other data types) :
List of datasets for machine learning research (Wikipedia)
Pytorch-repositories have many datasets for different applications (not sure where to put them, Romain Egelé):
ML challenges and benchmarks:
Inspiring blogs/resources:
https://paperswithcode.com/datasets: very useful, sorted by number of papers.
https://datasetsearch.research.google.com/ valuable for specific queries