Ok,
so
I'm an accessory guy
i LOVE eBay for low prices
but this thing is TOO DAMN NEW!!!
basically what I've found is the following:
as of right now when I post this the following is available:
Micro USB (a new standard) wall charger, car charger, and USB cable
Micro SD cards (phone supports up to an 8gb)
universal pouch cases (i agree with the VZN rep in that they're gonna have a difficult time developing a plastic clip on case or even a leather case much less for this phone without losing the functionality of the external touch.
the clip holster I got from the Verizon store
if you MUST have another battery, they're available from Motorola directly only at the time
for what I believe is $39.99?
the phone uses the BN61 battery, which also may be a new standard.
Keep this section active ma people!!
I will CONTINUE to post and update with new stuff and updates.    

That may be...
I'm just going off of what's on the VZW site, which is usually a "safe" statement.
I'm not sure what the original moto Q was rated at, 1 or 2 gigs,
but I used the sdhc patch on mine and got it to accept a 4gb, which is what I'm going to use on my Krave till I get sum mo $

Don't forget about the bluetooth accessories.

You've got the new version of the Motorola S9 stereo bluetooth and for the regular bluetooth headset there's the new Motorola H710 which is an upgrade to the H700 that had the issues with the flip boom wearing out.  It's too early to tell but they claim to have fixed this issue with the H710.

I do have a pair of these:

You can find them here: http://oakley.com/orokrpro
a bit pricey though.
They were a gift from a kind uncle.
GREAT sound, and also answered calls quite well.

The new S9 is supposedly HD so it's supposed to have better sounds.  I haven't tried them so I don't know if the low end bass sounds are better or not.  I bet the Motorola HT820 has some good low end though from the looks of them.