Yes you most certainly can. I play music through bluetooth on my car stereo, so no need to plug it in. The beauty about using USB, is that you can plug it into anything you want that has USB or 3.5mm jack (USB is the standard for ALL cellphones now BTW). You can even plug it into a computer, and it will open up a folder just like any mass USB storage device, and drag files on and off of the microSD card as you please. Dont have to install any required software or anything. And if one SD card gets full, take it out and put a new one in there.
If I'm at a friends house, and were doing a little gaming and my phone gets low, plug it right into the PS3 and it will charge, or if his tv is equipped with USB I can charge it there too. I can even give him some of my mp3's or noody pics, or steal some of his.
One of the things I like most about android is this. Think of your computer. Hit the start menu, click all programs. Now you see a list of programs in there, thats the iphone, thats all it is. Android is the desktop with the entire start menu as well. If I get tired of using windows XP, I can install Windows 7, or if I prefer somethings off XP and other things from 7, I can run a hybrid version, or add things from one onto another.
Iphone is good, but android makes up for the things that the iphone lacks, and none of the Apple bullshit that comes with owning an Apple product.