The key to many successful promotions is to make them fun. One fun way I heard of to promote your clearance items it to create a "Garage Sale" or "Yard Sale." It's a fun, easy, on-going promotion you can run year-round. Simply get a remnant of carpet (preferably green) and line a section of shelf with it. Put up a "Yard Sale" sign and rotate in your clearance items. You'll be surprised how many guys will rifle through these items looking for deals.
Be aware that price promotion means discounting. That money has to come from somewhere. It's fine if you're getting a discount on items from your flag or WD, or if you need to quickly dump overstock to free up cash. But any other discounting means you're giving away part of your margin -- so use it with discretion.
Have a sales strategy or helpful hint you'd like to share? Send your "30-second sales seminar" to firstname.lastname@example.org, and see your suggestion featured here!