I recently splurged on a pair of Shure's. I have to say...wow. My pocketbook hates me, but after using the POS iPod headphones for a few months I have to say I'll never go back.

To echo what oldskoolboarder says, these aren't good for work outs or really any kind of physical activity. Sound isolation is great for airplanes (which is a big reason I went for them) and for shutting out the world in general. For example, my cell phone was blaring a foot from my head and I couldn't hear it.