Sony Reader book cover - get it
I've had my 600 for a little over a month now and found it uncomfortable to read one handed while reclining.
The cover seemed a nice touch, but not realy that important. So when I received one as a late Christmas present I was happy but expected nothing great from it.
Much to my supprise I now find the reader very comfortable to hold in one hand. Even if others may have mentioned it, I havn't seen this anywhere else, and would like to strongly recommend it.