I listed bands and artists from different genres I know (I am 23 and like to think I am educated)
Indie: The Killers, Plain White T's, Oasis, Owl City, James Blunt , James Morrison, Maroon 5.
Punk Rock/Skater Rock: Greenday,Blink 182, Sum 41, The Offspring.
Pop: Take That, Westlife, Boyzone.
Pop Rock: The Hoosiers, Pink, Lissie, Counting Crows, Avril Lavigne.
Rap/Pop: Akon, Dr Dre, Eminem, Cee Lo Green, Tinchi Stryder, Flo Rider, Mike Posner, Black eyed peas, David Guetta.
Rock/Metal: Marylin Manson, Iron Maiden, Metallica, System of a down, Queens of the stone age, Trivium, Snow Patrol, Papa Roach,Foo Fighters Slipknot.
All popular in each category, not extremely well heard of if you are outside that genre.
P.s The songs are put into the categories I deemed fit (without getting into sub genres) this is not a point for debate people!.
Hope this helps