UCI database is a versatile body of pattern recognition data with associated literature and analysis.
Data has been sorted according to categories, which makes it specially for use by a diverse audience.
Here is the link for the data sets: [1]
Look to the fourth tab on the left,'Area', with categories of Life Sciences, Physical Sciences and so on. There are tens of data sets for each category. In each data set you will see a description of what this data set is about, description of its inputs/outputs and a few papers relevant to the data set. These papers may contain unique information about data set, and sometimes help preprocess or acquire useful features from data.
