  UPDATE: urlLink EFF: RIAA Subpoena Database : "Concerned that information about your file-sharing username may have been subpoenaed by the RIAA? Check here to see if your username is on one of the subpoenas filed with the D.C. District Court. This information is drawn from the court's publicly available PACER database and will be updated when that system is updated. " ..if you're american, and you've used kazaa, kazaa lite, grokster, etc, type in your username, and click "check". little easier... 
