Basically you can use any storage resource management (SRM) software package that supports the OS your files reside on. SRM software will help you gather the data, identify it and get a report detailed enough to take action. However SRM software only reveals the information but doesn't take any automated action like deleting or moving files, so you need to either write some scripts or make it a manual task. If you want to have your older files stored away to a place other than online storage (special drives, tape libraries etc.) using defined criteria like "not accessed within the last 30 days" you can implement an HSM system that can do the job. Most SRM software lets you query its repository from external processes, so scripting is possible.
The only SRM solution capable of automating this policy and task I am aware of to date is QiNetix from CommVault Systems. This system is capable of defining policies based on attributes of any file within the overseen realm and archive them according to the parameters defined (age, access, size, directory).