Looking for Predictive Modeling / Data Mining data set repository for demonstrations

Hi

I'd like to demonstrate a new data mining technique to a client, where the client can then gain access to the same data set and use their own favorite techniques and compare results to what I have demonstrated. I'd like to find a data set with a binary target variable and as many predictors (columns) and records (rows) as possible. Anyone know of a repository of such data sets? Domain (medicine, lending, etc) is not as important as the size of the data file to be tackled. Thanks