Product review (4 stars): Easy to Use Vent Cleaning System
We've been in our house 8 years now, and I never knew you were supposed to clean out your dryer vents.  Our dryer was starting to leave clothes damp, and after some internet searches I decided that clogged vents were most likely the culprit.  Enter the Gardus Linteater system.  I just got finished with my first cleaning about half an hour ago. The system is very easy to use.  A brush mounted on flexible extensions is fed into the duct either from inside or outside the house while at the same time the duct is being blown or vacuumed clean.  The Gardus system is easy to use and well made at a reasonable price.

After my experience I have a couple of words of wisdom.  First, they recommend adding tape to the brush extension pieces, which I think is completely overkill.  I snugged them with Vice Grips and they were very difficult to get undone.  Unless you run your drill the wrong direction the entire time I doubt they'll work themselves loose.

Second, I'd recommend blowing outside rather than sucking.  I originally set up my shop vac to suck, and was clever and plugged it in using a remote switch I had, so I could wait until I was outside ready to go before turning it on.  Things were going great for about the first minute until all my smoke alarms started going off.  Somehow a fair amount of lint managed to get outside the vac and covered my entire laundry room and part of my downstairs.  In retrospect I should have used the included vac attachment with the hole for the extension rod (I didn't realize it was in the box until I was finished) and done the cleaning from inside next to the vac, so I would have realized I was filling my house with lint.  That was all my own fault, and not the cleaning system.