Pop-Up Clogfree Drain, by PF Waterworks
The culprit in the clog is often the connecting rod, the part that raises and lowers the sink's drain stopper and catches hair and other gunk. The rod for this slick stopper plugs the hole from the old rod but doesn't protrude into the drain. How's it work, then? Magnets!
About $10; homedepot.com