David Letterman has never been shy about calling Foo Fighters his favorite band, and as the latest sales numbers from Billboard indicate, he recently got to promote Dave Grohl and company in a more indirect way. Following their performance of their 1997 song "Everlong" on the final episode of the Late Show with David Letterman earlier this month, Foo Fighters' 2009 compilation album Greatest Hits experienced a significant sales boost.

According to Billboard: "The band's overall album sales grew by 99 percent in the week ending May 24, while their song sales rose by 126 percent. Overall streams for the act also got a lift, rising by 17 percent. The band's best-selling album of the week, selling 7,000 copies – a gain of 166 percent. On the Billboard 200, Greatest Hits vaults from 141 to 56 with 11,000 overall units (up 132 percent), for its highest rank in over four years. It was last at a higher rank on the list dated April 30, 2011, when it was at No. 45."

The relationship between the recently retired Letterman and the still-kicking Foo Fighters goes way back: While introducing Foo Fighters before a 2001 performance on the Late Show, Letterman explained why they are his favorite band, and why "Everlong" is his favorite song, telling the story of how he band rushed back to New York from South America when they heard that Letterman had to undergo what he called "horrible heart surgery." The band performed "Everlong" on Letterman's first episode back at his request, of which he said, "The song that we asked them to do that night was I don't think a current song of theirs, but they were nice enough to do it for us anyway, and because of my condition and the coming back to the show after the heart surgery, the song has always meant something incredibly personal and intimate and important to me and to my family."

Foo Fighters – "Everlong" (on the Late Show with David Letterman)