Das Dataset Search Tool von Google ist offiziell aus dem Beta-Stadium (via SearchReSearch):
«You can use it to find open-access datasets. Just search on the topic of interest and you’ll see a list of results on the left-side, and a summary of the dataset that’s selected. For example, here I’m searching for datasets about snakes… (…)
As it stands now, Dataset search indexes around 25 million datasets. Surely there’s something of interest to you in there!»