Mazda Service Manual
My 2002 Mazda Protege was idling a bit slowly, and I found that I can't by a Haynes manual yet for a car this new. (With over 76k miles on it, it's long out of warranty.)
I fortunately managed to find a copy of the 2002 shop service manual online, and it led me through a few troubleshooting steps. Along the way, the checking and reseating plugs and vaccuum lines seems to have fixed the problem, so it's running fine now.
This online manual may sound like a treasure trove of information, but the chopped up PDF format makes it a bit hard to navigate. I could barely figure out that "IAC" stood for "Idle Air Control", much less where it actually exists on the car. The section on checking this component didn't seem to have a diagram of where it's found, so I'll still be hoping to pick up a Haynes manual for the common layperson when it comes out.
A couple weeks ago, I found another manual for my car, ExtremeTech's Geek My Ride. It's a book about adding toys (game consoles, media PCs, general PCs, displays, etc) to a car. It's supposed to be good advice for any car, but I noticed in all the photos that they're example car looks just like my 2002 Protege. I wouldn't mind reading this book for ideas on providing power, automatic powering up and down, and non-distracting input methods -- it seems to have all this. It's definitely tempting to try to tech out my car just for the hell of it. The hardest part appears to be scraping together cash to buy all the components.