Product review (5 stars): Gardus RLE202 LintEater 10-Piece Rotary Dryer vent cleaning system
Another one of those "I wish I'd invented this!!" sort of products.  We have a 20' run of aluminum venting from the dryer to the great outdoors.  This did a great job of cleaning out the inside of the pipe better than any yardstick I ever used.  This is yet another product that deserves more than five stars.  Ialso bought the extension kit.  Follow the directions and all should be well.