The Reach Access Flosser makes flossing very quick and easy! 

The unit is designed to keep the dental floss tight so it slides in between teeth very easily.  I've heard that the string breaks easily between tight teeth, but I've never experienced that in the 18 months or so of using it.

The only downside that I've seen is the cost.  The inital unit costs about $5 and the replacement heads are about $3.50 per month.