'HIGH SCHOOL MUSICAL' The companion CD to Disney's TV movie moved 3.7 million copies and was the year's top seller. The last soundtrack to claim that feat? No shock here: Titanic in 1998.

JOHNNY CASH The Man in Black still has a devoted fan base: He was the year's second-best-selling artist. His entire catalog — including one set of new music and a fistful of compilations — sold 4.8 million copies in '06.

HIP-HOP Not even Jay-Z (whose big ''comeback'' album, Kingdom Come, sold one-million-plus units) could salvage a dismal year for rap. The genre's sales saw a 20 percent year-to-year slip.

COUNTRY It's no longer playing second fiddle to pop, boasting 5 of the year's 10 best-selling artists — including Tim McGraw (No. 6) and Keith Urban (No. 9).

DANIEL POWTER A case study: His ubiquitous ''Bad Day'' was the No. 1 digital song of 2006, with more than 2 million downloads. (Thanks, Idol!) On the flip side, Powter's CD has yet to go platinum. Aha! So that's why Tower Records went kaput.