Jason Wilson has a nice story in the Washington Post on the rickey cocktail. I didn't realize it was named after a person and invented in DC. He also took a bar tour to taste some local variations of the drink as part of Rickey Month in DC. This one is my favorite:
I take my hat off to Justin Guthrie, bar manager at Central and winner of the rickey contest, who made a delicious black pepper-lime soda, simply mixed with gin over ice, that also ratcheted up the rickey's flavor quotient.