The Abbey Bookshop (29 rue de la Parcheminerie in the 5th), run by an affable Canadian who moved from Toronto in 1994, is one of the most stock filled spaces I have ever been in. There is hardly any room to move without knocking over piles of new and used books. Good news for lovers of the word and especially the Canadian word.
The poetry selection was comprehensive with classics and current volumes, but as ever the mark up on new books is high. The second hand books however were reasonably priced and I picked up a couple of things I have missed in recent years.
Unbelievably the bookshop holds occasional events. When I asked a friend later where and how, he explained that that was what the summer streets are for - ah Paris!
Details here: http://www.alevdesign.com/abbey/abbey_en.html