In 2001, two brothers from the group Soulwax released a mashup album titled "2 Many DJs." Each mashup paired a vocal track from one song with another song's instrumentals. Freelance Hellraiser's mix of Christina Aguilera's "Genie in a Bottle" with The Strokes' "Hard to Explain" proved one of the most popular tracks; Village Voice writer Douglas Wolk described the song, titled "A Stroke of Genie-us," as the best knew song he'd heard in a year. The song "Smells Like Booty" combined Destiny's Child's "Bootylicious" and Nirvana's "Smells Like Teen Spirit." The album set a precedent for the mashup genre to follow the formula of adding two songs in an "A +B" formula. David and Stephen Dewaele, the producers of the album, spent more than half a year getting permission to use all the tracks included on the album.
2001 saw the release of another mashup album produced by DJ Z-Trip and DJ P, titled "Uneasy Listening Volume 1." The album contained mashups of music from the 1960s to the 1990s, featuring samples from Metallica, Public Enemy and AC/DC. At the 2001 BRIT awards, Kylie Minogue showed her support of the mashup genre when she performed "Can't Get Blue Monday Out of My Head," a Soulwax mashup of her own song and a New Order track called "Blue Monday."
In 2004, DJ Danger Mouse released The Grey Album, combining Jay-Z's "Black Album" with the Beatles' "White Album." This album followed the established A+B mashup formula for an entire album rather than an individual track. The album spurned wide debate about copyright laws and the legality of sampling. The album also inspired many imitations and spoofs, including a mashup of Jay-Z and Weezer titled "Jay-Zeezer: The Black and Blue Album."
In 2002, Gregg Gillis released the album "Secret Diary" under the name of Girl Talk. This album and subsequent Girl Talk albums, including Unstoppable (2004), Night Ripper (2006) and Feed the Animals (2008), broke from the early mashup formula of combining only two songs into one. Each Girl Talk track typically includes samples from more than ten different songs from all different music genres, including rock, pop, hip hop, folk and indie music. The record label Illegal Art released all four Girl Talk albums.
The appearance of mashups on television indicates the mainstream status the genre has achieved. The eight episode of Fox television series "Glee" involved the characters' attempt to combine the "Thong Song" by Sisqo with the "My Fair Lady" classic "I Could Have Danced all Night." Several mashups also appear on the "Glee" soundtrack albums.