I spent all summer trying to correct my slice. I managed to almost eliminate it completely. Unfortunately, the total overhaul of my swing ruined every other club.
Anyway... what finally worked to correct the slice was bring my hands in closer to my body. This caused the arc of my swing to be more up/down and less of a horizontal circular motion.
(obviously there were other adjustments also, like bring my top hand more over the top and concentrating more on locking my front arm, but the hands in closer to the body was the biggest improvement)
You are probably a better golfer than I am, but it was worth a mention since that one thing made a HUGE, all-of-a-sudden, difference in fixing my slice.
- Aetherial
I used to have a horrible slice off the tee. I fixed it by strengthening my grip (ie: turning your hands slightly counterclockwise on the grip). It feels a bit weird at the start but really works.