I'd like to nominate The Fame Monster by Lady Gaga. If you compare it to competing albums at the time of its release and the overall period of music in which it dropped, it really is a fresh piece of music. Considering Gaga wrote every song on the EP, I think that furthers its significance in the 2000s decade of music. Bad Romance, Telephone, and Alejandro topped charts everywhere, with Bad Romance and Telephone becoming two of the best-selling singles of all time (Bad Romance recently attained the Diamond ranking, selling 10x Platinum, meaning 10 million copies).
Bad Romance's video was arguably the most culturally impactful video of the 2000s. Alejandro sparked controversy over its gay-influenced innuendoes, and Telephone came close to matching Bad Romance's success with its seven-minute film featuring Beyonce and Gaga going on a murder rampage.
The EP isn't just about the typical cliches of the 2000s (sex, money, drugs), it's a commentary of the underbelly of fame and new liberal developments in the 21st century. Dance in the Dark details a girl's insecurity about her body, So Happy I Could Die details Gaga's fear of addiction and alcoholic influence, and Teeth chronicles Lady Gaga's fear of the truth.
Perfect EP, honestly.