I use (gasp!!!) a Zune. I LOVE the Zune Pass... I am all about the idea of renting things. I only own a couple of movies as I only watch a movie once (rarely twice) in my lifetime and therefore renting works for me. I am the same way with music... I get into certain bands for awhile and then never want to hear them again. Also, when I get a horribly trendy and catchy song stuck in my head (Katy Perry's "I Kissed A Girl") I can download it, overplay it until I want to vomit, and then delete it without being charged .99 for a song I don't want to keep for life. When I really love a band/album/etc. I will pay for a CD (I like getting the artwork, etc.) and then rip it onto my Zune.
Also, I love the idea of the Zune Pass because I can be daring and try out a new band I have never heard of without it costing me a dime (just the monthly rental fee for unlimited downloads.)
For me it is about saving money WITH the ability to be adventurous.
I still use my 3G Nano everyday, mainly to help preserve my iPhone's battery life if I'm gonna be out an about all day long and unable to use my car or wall charger. I've noticed too that sometimes the iPhone iPod's playback gets choppy if you're using a resource intensive App at the same time, so I stick with a dedicated music player.
I also use the Nano for running (Nike+); even if the iPhone supported Nike+ there's no way I'd use it, it's just too big and heavy compared to a Nano.
I have a 16gb 3G iPhone and an old 80gb iPod. The iPod stays home now with all my music on it while the iPhone gets loaded with a few (16gb) essential tracks for mobile listening. It's gonna be a few more years before iPhones reach the iPods capacity. The bummer is you can swap out the iPods HD but you probably can't on the iPhone.
I have music on my iPhone but rarely use it for music. I use my 80GB iPod to power my car stereo and to get me through work.
When I first got my iPhone 3g 16GB I stuck with my 80GB iPod for a month or so since I have about 36GB of music, but now I rarely use my iPod. I just put on the music I listen to more on my iPhone and it's one less thing to carry around.
I have an 80GB Classic that stays in my car 24/7 hooked up to my head unit. If I wasn't so obsessed with music, or couldn't afford a head unit with a direct dock connection, I wouldn't have 2 Apple music devices.
I use a 30g Video iPod in the car - always hooked to the stereo (unless I get some new music and need to sync). For running, the shuffle is the only way to go. I have songs on the iPhone but I rarely use it for playing music. However, I have used it to watch a couple of movies while flying. Anyone have their iphone connected to a car stereo when a call comes in? What happens?