The most influential album of the past quarter century celebrates its 20th anniversary with several new reissues. The priciest is a four-CD, one-DVD box that includes a different mix of the record plus a complete concert. But most fans will be happy with the two-disc set that tags on B-sides, radio sessions, and some rehearsal demos. Listening to early raw versions of Nevermind classics such as "Smells Like Teen Spirit" and "Come As You Are" evokes Nirvana's punk roots, but they don't pack nearly as much force as producer Butch Vig's finished product. And after all these years, the album still sounds like the industry-shattering revolution it instantly became. You may be tired of these songs by now, but give this reissue a spin to remind you why there was no turning back after this.