i purchased a daily planner from the evil Walmart. and unfortunately for me, it works fine and cheap.
when i took out the daily planner part, I slid the back part of the sony cover into the center divider (just like the planner was inserted). When I am travelling, there is a spandex strap that I can place over the reader to kinda secure it. (it's not like I am running a marathon people, and it is a piece of electonic so I am not going to be playing frisbee with it)
the front section has a place for a business card or id card and a small 5" x 6" section to place documents (albeit small documents) there. next to the divider and not rubbing against the reader is a little spandex loop for a pen (Cross pen size)
then i flip the center divider (which the sony reader is attached to) and there is another slot for a business card and holder for a small piece of paper. then on the back side of the case is a place for a small tablet of paper (which comes with the daily planner).
The only cons are that the case is not zippered but sort of strapped in like the cases Amazon is offering for the 505's, but again, I use the spandex strap to hold it in. and that you are now carrying something comparable to three 505's stacked on top of each other (8.5" x 5.5" and 1.5" thick).
but it works.
and now i realize that i can't use the new amazon covers with this because the reader is secured with loops on the back side of the cover and i need that back side to be free so i can insert it in the plastic divider.