It took about 5 days of calculation to redo the feature extraction on all of the music on needle, excluding silence.

The only metric I have for generated playlists is my happiness with them. After a days playing around, I think there is a subtle improvement, now that the silence is being ignored:

1. Only -- Nine Inch Nails
2. Maria, Maria -- Santana
3. Buddy X -- Neneh Cherry
4. Who Knew -- Eminem
5. Maria Maria (feat. The Product G&B & Wyclef Jean) -- Santana
6. 10,000 Years (Peace Is Now) -- Live
7. My Sharona -- The Knack
8. The Chastising of Renegade -- Primus
9. Open All Night -- The Urge
10. Monsoon -- Robbie Williams
11. Girl U Want -- Devo
12. Educated Fool -- Hoobastank
13. Azwethinkweiz -- Incubus
14. In the Midnight Hour -- The Commitments
15. Hope -- Screaming Headless Torsos
16. The Man In the River -- Bootsauce

Next step is to take "ratings" into account. That's going to require a bit more work, though.