KLEER DRAIN INSTANT DRAIN OPENER
Both of my bathroom sinks drain very slowly and nothing I've used works to clear it. Mark Frauenfelder over at Boing Boing gave a rather convincing testimonial as to its effectiveness. It just may be worth a shot, with the exception of the shower of gray grime.
The only thing that concerns me is that I have no way of removing the stopper and it looks like you need to be able to do that to allow maximum air flow.
Of course I DO live in an apartment so I could make them come and fix it, but I REALLY hate having people I don't know come through my house. It's quite the dilemma.