A lot of new sub-blogs have popped up recently, and as I can't find an already-existing directory, I'm making one here. Please add any link I forgot in the comments.
Users' Forum: oppositelock.jalopnik.com
Motor City News & Commentary: detroit.jalopnik.com
/Drive Youtube Channel: drive.jalopnik.com
Trucks & Pickups: truckyeah.jalopnik.com
Random Dude from Hotlanta: dougdemuro.jalopnik.com
Aircraft & Planelopnik: flightclub.jalopnik.com
Military Topics: foxtrotalpha.jalopnik.com
Press Releases: releases.jalopnik.com (Not updated since December 31, 2013)
There are also some important multi-author kinja.com blogs, some of which are listed below. Please add any others you would like to see in the comments.
Motorsports News & Commentary: rennsport.kinja.com
Road & Track Magazine: kinja.roadandtrack.com
Racer Magazine: racermag.kinja.com
NASCAR: winonsunday.kinja.com (Not updated since October 16, 2013)