add a keyboard shortcut for closing the current item
I like the new keyboard shortcuts (as of 1 May) but you appear to be missing one for closing or collapsing the item that is currently being read. In Google Reader it's 'o'. Since you use that for opening the post in a new tab, you might use 'x' which would match up nicely with Shift+x (collapse selected folder).
Because most people use one hand to use it, I like the 'o' to do this, so i can quickly to use j,k,o, can you change ?