The MATCH utility
Match is a program that can match sets of experimental stimuli. Match can match on as many properties as you want, and properties can even be assigned a weight to reflect their relative importance for matching. Correct values for all properties to match on have to be provided, though.
Match can be downloaded, with a manual, by going to this page: http://www.mrc-cbu.cam.ac.uk/people/maarten.van-casteren/mixandmatch.html