HAha Adam, I've sworn off the Jack Daniels for many a year now. Was more of a rock thing. Worked wonders with those dudes at times, especially the cokeheads, and totally made a track (the whole pint!) with Tim from Hemigod (Atlantic). I'll never forget that take.
One night, another Radioheadesque act's singer was feeling plastic, so we went to Gusoline Alley, just up the railroad tracks in Royal Oak, MI, and got real lit up with Vodka whilst listening to their juke box, voted the best in Detroit. Raw rock jukebox, vodka, got back to the studio and suddenly this guy was Mick Jagger. One take AND the ruff mix from that night (lacking lot's of highend!) went on the final record.
I'm not advocating drinking in the studio anymore though. I'm also doing alot of hip-hop and R&B now. Alot of music where the attitude of the vocalist has to be just right. Alot of people just start getting into their groove after 15 or 20 minutes, with some direction. "Now bring the swagger!" is the general direction given time and again.