FYI for future reference and those that google for a similar issue. If
tightening packing nut did not solve the original posters question then
the next steps would have been as follows:

Shut off water at the main
Remove the handle (One screw at the end of the stem)
Remove the packing nut (Lefty loosey)
Wrap new packing material around stem
See
http://www.lowes.com/lowes/lkn?actio...153-1366-80793
or
http://www.builderdepot.com/browse.i...odstoreid=1735
or http://www.hardwareworld.com/Graphit...g-p9W7BD5.aspx
Replace nut (Righty tighty)
Replace handle
Turn on water and check for leaks