Madonna's U.K. Chart 'Celebration'
Singer Madonna performs on stage at Vicente Calderon Stadium on July 23, 2009 in Madrid, Spain. Getty

"Love the Way You Lie," by Eminem featuring Rihanna, is the 46th Billboard Hot 100 No. 1 since 2000 specifically sporting a "featuring" artist credit.

Between 1958 and 1999, just 18 such titles reigned.

Still, high-profile acts have guested on hit songs throughout the rock era, even if they didn't always receive official billing on single releases.

"Artists used to (make cameos) as more of a favor to each other. Record labels weren't the all-controlling conglomerates they have become, so it frequently went unnoticed," says Barry Scott, who has hosted the radio program "The Lost 45s" for more than 25 years. The weekly show spotlights songs that reached the Hot 100's top 40 from the '60s through the '80s but rarely receive airplay today.

"Plus, when buying LPs, everyone looked to see who the other players on the tunes were, from drums to backing vocals; that was the beauty of holding an album or even a 45 in your hand," theorizes the Boston-based Scott. "The artist received credit in that manner.

"It is difficult to hold an MP3 in your hand, unless it's in a memory stick."

Scott cites a song that entered the Hot 100's top 40 32 years ago this week as a contrast to today's more complex music industry.

"When 'Whenever I Call You 'Friend' ' by Kenny Loggins was released on Columbia in July 1978, Warner Bros. didn't bat an eye that one of their biggest stars was a very noticeable uncredited special guest: Stevie Nicks. (Although the part was originally going to go to Loggins' co-writer, Melissa Manchester, the authors agreed that Nicks would be better suited for the song).

"Once (such appearances) became common practice," says Scott, "it was too late to go back for a variety of monetary and legal reasons."

In the spirit of celebrating the contributions of artists not appearing on vinyl or CD picture sleeves (and not adding to their Hot 100 histories), Chart Beat looks at some of the best-known songs sporting somewhat stealthy guest appearances.

"You're So Vain," Carly Simon

Is the song about Warren Beatty? David Geffen? Mick Jagger? While Simon has never ended all speculation, what is confirmed is that Jagger sings backup vocals on the single, which ruled the Hot 100 for three weeks in 1973.

"I Guess That's Why They Call It the Blues," Elton John

The Rocket Man played piano and enlisted the talents of Stevie Wonder to supply the track's trademark harmonica flourishes. The song reached No. 4 on the Hot 100 in January 1984.

"Somebody's Watching Me," Rockwell

Rockwell was born Kennedy Gordy ... the son of Motown founder Berry Gordy (although the singer reportedly earned his record deal with the label without his father's knowledge). Not only does Michael Jackson sing the song's chorus, but another childhood friend of Rockwell also provides vocals: Jermaine Jackson. "Somebody's Watching Me" reached No. 2 on the Hot 100 and spent five weeks atop R&B/Hip-Hop Songs in 1984.

"Money for Nothing," Dire Straits

"I want my MTV," sings Sting on the wry ode to rock star excess. The song became Dire Straits' sole Hot 100 No. 1 for three weeks in 1985.

"Take a Bow," Madonna

With background vocals and production from Babyface, Madonna scored her longest-reigning Hot 100 No. 1 (seven weeks, 1995). The lush ballad also remains her last top 40 hit to-date on R&B/Hip-Hop Songs (No. 40).

Un-Featured Featured Artists, Part 2