supafresh - 9:58 pm on Dec 1, 2011 (gmt 0)
If you could share your method with us, it would be greatly appreciated.
In analytics click on Traffic Sources
Click on keywords
Click on (not provided)
Click on the dropdown that displays none below site usage.
Click on landing page
Now you can see what landing pages received traffic from non provided search queries.
If you know what your landing pages are optimized for you can figure out what keyword it probably was.
Itís not perfect but it gives you a rough idea what keyword it could be.