We went to The Columbia Room for Jon's birthday, wherein Audrey had and enjoyed a White Lady cocktail. We've begun researching and working on our own version. Wikipedia has an unusually detailed article on it:

2 parts gin (Plymouth or other medium-body gin, not a super-botanical one)
1 part lemon juice
1 part Cointreau

Sugar the rim of a wine or martini glass

Shake rigorously, serve. Squeeze a lemon peel over the drink and then use it as a garnish.