I have developed a macro-enabled Excel program that creates datasets of variables with user-specified correlations. The program accommodates normal random variates, scale variables with specified mean, standard deviation, etc. and/or binomial variables. It is freely available; please share it with others.
Here is a link to a CODAP document that does something similar. Though the only slider showing is for r-squared, if you move the text component you will find collapsed sliders for the other parameters ready to uncollapse and play with.