Talks of a Bieber-Kanye-Raekwon collaboration started when West initiated the collaboration with Twitter invitations for both artists to come to his studio. What blossomed from these tweets was “Runaway Love Remix.” Even wilder than the collaboration itself was its use of the “Wu-Tang Clan Ain’t Nuthing ta F’ Wit” sample, a hard-core hip-hop song that jumpstarted Raekwon’s career in 1993.

But the song’s hard-core background mixed with soft piano chords and a young Michael Jackson-esque Justin Beiber made a hit out of what could have been a train wreck. Not only did it create a bridge between two polar music genres, it also brought veteran hip-hop artist Raekwon to a new generation of bloggers and Beliebers.

While not all collaborations outside of the hip-hop sphere end in chart-toppers, some unusual pairings of rappers and singers or pop artists have broken down barriers and bridged genres in music. The following is a list of the most experimental hip-hop collaborations that actually produced quality material:

Run-DMC & Aerosmith-“Walk This Way”
This record is the cream of the crop, the alpha and the omega, and king of all kings. Run-DMC’s cover of the 1975 Aerosmith song for their 1986 album, Raising Hell, opened many doors for the music of the future. First, the song brought Aerosmith back into the limelight in the ‘80s, resurrecting their career and making them cool once again. Second, the song created the first bridge between hardcore rock and hip-hop, creating a sense of mutual respect for both genres from diehard fans in the ‘80s. Without this collaboration, many hip-hop relationships with artists outside of the genre, along with the songs heard on the radio today, probably would not have been established. If any collaboration deserves the title of being the weirdest, it should be Run-DMC and Aerosmith. But if there is an award for most influential song of the past 30 years, they probably deserve to take that one too.

M.I.A. ft. Jay-Z-“XXXO (Remix)”
Jay-Z shocked millions of fans when he appeared on the remix of M.I.A.’s most recent hit, a techno-inspired, synth-heavy dance song. Other than hearing Jay-Z say “metro sexual” with a Brooklyn accent, it’s nice to hear the self-proclaimed God MC spread outside of a genre that has done so much for him.

Bone Thugs-N-Harmony ft. Phil Collins-“Home”
Back in 2003, Bone Thugs sampled the 1985 Phil Collins song “Take Me Home.” What grew from that sample was an introspective look at the hardships of life on the streets and the hope for a better life in the future. Though calling Collins an honorary member of the hip-hop group (unofficially named Chrome Bone) might not have been such a good idea for their street cred, their collaboration definitely was.

Eminem ft. Dido-“Stan”
At the turn of the millennium, Eminem was the hottest rapper on the streets and the radio. So when he decided to sample hit British singer Dido’s “Thank You” as the hook for “Stan,” it seemed like the perfect match. The song is about a fictional Eminem fan that writes him mail professing his love and support, gets angry when he receives no reply, and eventually kills himself in a car crash. It fits perfectly with Dido’s mellow voice in the sample, making a perfect pair that captures the thin line between fans and fanatics.

Nelly ft. Tim McGraw-“Over and Over Again”
When Nelly dropped two full-length albums on the same day in 2004 (Sweat and Suit, which took over the #1 and #2 spots on Billboard Top 200 Chart), he decided to take an even greater risk by venturing into the country genre in this stunning collaboration with country star Tim McGraw. While making a song about lost love might not be so original, McGraw’s emotional hook mixed with Nelly’s sing-songy flow make an unlikely pair with a moving duet.

Wale ft. Lady Gaga-“Chillin”
While he wasn’t busy performing in shows around the country, signing papers with Jay-Z, and reppin’ D.C., Maryland rapper Wale decided to hold off on his “mixtapes about nothing” and put out a debut album. Of course, the only way to arrive in style to the mainstream hip-hop game is to have Cool and Dre sample Steam’s 1969 anthem “Na Na Hey Hey Kiss Him Goodbye” and put Lady Gaga on the hook. But Wale pulled it off, and he pulled it off well.

Jay-Z & Linkin Park-Collision Course (album)
This collaboration is neither a single nor an original production, but the EP has sold 2 million copies in the US alone, so it has to go on the list. What started out as a mash-up for an MTV performance slowly blossomed into a full-blown EP between hip-hop mogul Jay-Z and rock band Linkin Park. What’s interesting is that some of the vocals were re-recorded to better fit the mash-up, which might not seem as noticeable to the average listener but is definitely a deciding factor in its replay value.

Coldplay ft. Jay-Z-“Lost+”
While Jay-Z did collaborate with Coldplay singer Chris Martin for his 2006 record “Beach Chair,” this version of Coldplay’s “Lost!” from their 2008 album Viva La Vida turned heads after he performed it at the 2009 Grammy Awards. Jay-Z takes the time to reference KRS-One (“suicide, it’s a suicide”), dust the critics and haters off his shoulder, and add himself to a list of martyrs that includes Martin Luther King and Malcolm X in the song.

T.I. ft. Lady Gaga-“Lick It”
There isn’t much to say about this record, considering the fact that it hasn’t been released yet, but a prospective collaboration like this is too unusual to miss. Of course, this article is probably the first place you will hear the news, but hopefully Lady Gaga can bring out her infamous individuality on the record, while T.I. can bring his southern swagger mixed in with his classic voice to match.

Kanye West ft. Rick Ross, Jay-Z, Nicki Minaj & Bon Iver-“Monster”
West’s album promotion has been blowing up the Internet for the past two months. With his plan to release a new song every Friday until Christmas, dubbed G.O.O.D. Fridays, Kanye has been treating fans and critics to star-studded sneak peeks of the sound he has been creating in Hawaii. Early September proved no different, with this track featuring a star-studded cast of new and familiar faces. Bon Iver, an indie-folk band headed by singer Justin Vernon, provides a soulful intro and outro for the track, while Rick Ross has a short but swagged-out opening before the chorus (only four bars of mayhem). While the writer might feel that long-time collaborator Jay-Z had the best verse on the posse cut, it’s widely agreed that Nicki Minaj steals the show, as the Young Money rapper spits 32 bars filled with brain-eating, Middle Eastern climates, spelled out curses, and Barbie dolls, all done in different voices and styles that vary every couple of lines.