Great product that Crutchfield gives you for free
1992 Geo Tracker
Crutchfield Customer Review (What's this?)
Although this is free from Crutchfield, it makes installing your CD player a very easy "plug-n-play" job. You pretty much just match the colors, red to red, black to black, yellow to yellow (these are for power). The rest are for speakers (gray, white, green and purple). The only thing, is just make sure you set the positive with the positive, and negative with the negative (negative has a black stripe). Other than that, it's pretty easy. Also, makes it that you don't have to cut any of your factory wiring harness.
Pros: it's free, and makes hooking up a head unit a BREEEEEEZE
Cons: Nothing really.. It's free....