I'd really like to see bottom attachable extension modules.
Some with extra plugs, others with extra buttons, extra batteries.
The most of the above I'd like, would be a 1.8" 20GB/60GB/80GB/120GB external battery powered hard drive. (i.e. just the battery and hard drive of an ipod)
Put that inside an attachable module and it would rock. [Note: if I stand correct, USB 2.0 is much faster than SD cards.]
eSATA port... hmmmmm. one can only dream...
People!!! Better start buying the Pandora en masse, so that we can see accessories and software popping up for the pandora.
Any of the hard drives you mentioned could easily be powered by USB. For instance, I use a 125 GB Laptop HDD in an external enclosure that only has one USB cable and that handles power as well as data.
As far as greening the entire list, negative. Until one of us actually sees it working with the Pandora, then it doesn't go green. Otherwise, we'll end up finding the one USB device that's somehow incompatible with OMAP or something crazy like that.