The Last Stack
I spent today book-shopping. Traded in my old books at Good Day Books, although they wouldn't take three of them (had copies already). Went to ABC in Roppongi to spend some book vouchers I got for helping with kanji learning research. Asked the ABC Outlet Store whether they bought used books; they don't, but the storekeep suggested The Blue Parrot Bookshop, near Takadanobaba. The fact that "near Takadanobaba" is awfully vague directions didn't deter me from going there and looking. I found it eventually, sold my last three books, and bought one more.
As far as I can tell, The Blue Parrot offers a little less in trade than Good Day Books, but their selection is still good and their prices are significantly lower. Also, you can sell books for cash (they'll offer you only a fraction of the trade value, but it's still a plus to have the option, IMO). Wish I'd discovered them earlier.
Update: Also wish I'd found this Ask MetaFilter post on English-language Tokyo bookstores earlier. Found it when I was looking for ABC's website.
As far as I can tell, The Blue Parrot offers a little less in trade than Good Day Books, but their selection is still good and their prices are significantly lower. Also, you can sell books for cash (they'll offer you only a fraction of the trade value, but it's still a plus to have the option, IMO). Wish I'd discovered them earlier.
Update: Also wish I'd found this Ask MetaFilter post on English-language Tokyo bookstores earlier. Found it when I was looking for ABC's website.