At GetTheData, you can ask and answer data related questions. Here’s a preview:
I’m not sure a Q&A site is the best way to do this.
My pipe dream is to create a taxonomy of variables and instances, and collect spreadsheets annotated this way. Imagine doing a search of type: “give me datasets, where an instance is a person, the variables are age, gender and weight” – and out would come datasets, each one tagged with the descriptions of the variables that were held constant for the whole dataset (person_type=student, location=Columbia, time_of_study=1/1/2009, study_type=longitudinal). It would even be possible to automatically convert one variable into another, if it was necessary (like age = time_of_measurement-time_of_birth). Maybe the dream of Semantic Web will actually be implemented for relatively structured statistical data rather than much fuzzier “knowledge”, just consider the difficulties of developing a universal Freebase. Wolfram|Alpha is perhaps currently closest effort to this idea (consider comparing banana consumption between different countries), but I’m not sure how I can upload my own data or do more complicated data queries – also, for some simple variables (like weight), the results are not very useful.