We just couldn’t stand to send another year-end list wriggling for water in a beyond-crowded fishtank, bearing tiny teeth if you disagree with where we placed Sound Of Silver (for the record: #19). And, seriously, who wants to spend a late winter night calculating just how many albums adequately prove that we’re aware that dubstep exists. So, for the second year in a row, we’ve gone with our guts instead of our Excel tallies.

We asked more than 30 of our favorite music writers to pick just one song that sums up 2007—one fragile, downloadable fragment to drop in our time capsule, to be buried deep under the cornerstone of the PTW servers. We’ve collected all of them here as the Paper Thin Walls 2007 Mixtape, two CD-Rs worth of the familiar and the alien, the hits and hits that should have been, Bible-versed power-pop and environmentally conscious black metal. Our list is not ranked, not very scientific and not exhaustive at all. But every song on it is a number one to somebody. (Or, in a few cases, the closest thing to a number one that a record label would let us post for free… -ella, -ella, -ella, etc.)

Besides a ringing endorsement, each song comes with a short conversation with the artist about what inspired it, how it evolved and, in one case, a brief explanation as to what exactly is an “Aerosmith gun.” We’ve posted all 32 MP3s, so please feel encouraged to download all the songs and burn them to CD (once again, they fit very neatly on two discs). But get moving, since when the silver ball drops on ’07, our cruel, vindictive webmasters (and thorough legal team) are dropping the free tunes as well.

The most anticipated album of the year didn’t cost a penny—and yet we still whined about the bitrate. How could this year possibly be any good?

On this year’s finest major label record, Against Me! made their dissatisfaction clear: “We can be the bands we want to hear/I’m looking for the crest of a new wave.” Too bad everyone else was still trying to feel around the current one. Music videos had to fit in an awkward two-inch screen. Major label rappers fought to see whose beat was the hottest once it was converted to 128kbps, truncated to 30 seconds, played over a speaker the size of a thumbnail and heard through a layer of denim. In the far more insular world of indie rock, last year’s Person Of The Year (you.blogspot.com) got grinded into the cold gears of the Hype Machine; it’s no longer about what people say, but just how many people say it—numbers, science, statistics. “You check the charts and start to figure it out,” as LCD Soundsystem’s James Murphy gasps on the era-defining “All My Friends,” before holding our hands through another 10 years of existential crises.

Disc One: You Said You Wanted Pop But Instead You Got This is full of bands figuring things out, creating new languages, dwelling in ambiguities. Battles spent a year letting their fans bark out whatever lyrics they wanted to a mysterious seven-minute Bolan/Elfman art-twurk; Dan Deacon soldered his own mutant electronics rig and became an instant pop star; Justice clicked a distortion pedal on the dance floor and became instant rock stars; Castanets roamed around searching for who knows what; Lavender Diamond smile bright because they think they found it; Of Montreal thinks maybe partying will help. On the opening track, Los Angeles motivational tweaker Barr explains the musician’s dilemma in meta-narrative “The Song Is The Single.” His plain-spoken shiver breaking down the joy and futility and contradictions of trying to make music in a fickle, broke, unpredictable, frustrating underground, including the lyric that gave this disc its name. Keep the car running.

Conversely, according to Spoon’s Britt Daniel on “You Got Yr Cherry Bomb,” “Life can be so fair, let it go on along.” The Rock Against Bush era is a distant memory, though dude is still taking up the same space in the same office. We’re running down the clock, going through the motions, waiting for regime change or environmental annihilation to just happen around us. As the National say, we’re “Half awake in a fake empire,” so we’re more and more comfortable with repetition, predictability. Do we love Lil Wayne because his mixtapes really have the best rapping, or just because he’s the best at rapping over songs we already like? Why are we still hearing Carrie Underwood and Amy Winehouse singles that broke in the fall of ’06? Yeah, we know that “Beautiful Girls” is just “Stand By Me” with Autotune, but let us play it one more time, k?

Disc Two: To Feel Alive When Nothing Ever Changes is about embracing the familiar. M.I.A. rides a Clash sample and a Wreckx-N-Effect lyric to fight government abuse; veteran rappers like Sean Price, Project Pat and Little Brother stick to their winning formulas and make their best art to date; black metal band Watain accidentally falls into the ’80s thrash that weaned them; Black Dice just glue together the parts of songs they like; and Cali droner Axolotl plays one note for four minutes. And no one sounds more alive than art-wheedle guitarist Marnie Stern, who’s donated her joyful exclamation from the aptly named “Logical Volume” to the title of the disc. Her comforting shout pushes along a feeling of familiarity and warmth in a song that already pays lyrical and musical tribute to her heroes. Can’t tell us nothin’. - CHRISTOPHER R. WEINGARTEN