I have been using the pop-up Japanese-English Dictionary Rikaisama very successfully for the last few weeks. It works with the Firefox browser on Windows and as you move the cursor over a web-page it shows the character(s) with reading in hiragana and meanings from the Edict dictionary project. You can tailor and save the pop-up information to the clipboard, a file or to Anki cards.http://rikaisama.sourceforge.net/
Rikaisama is an add-on to Rikaichanhttp://www.polarcloud.com/rikaichan/
It does of course make it possible to buy books that you didn't know you needed.....
If you want to buy second hand Go books from Amazon or Yahoo Auctions then the web-site Buyee.JP works wonders - warning - you can give your credit card a bit of a shock. Let me know if there is any interest on a separate post on Buyee.JP