The Home page has a little more information.
I am author of GOWrite. GOWrite is free full featured SGF editor for GO. Its main strength is in good publication features (EPS and Windows metafile formats). GOWrite is used by several book and magazine authors.
Current GOWrite version is Java based and uses SGF format 4. It works at least in Windows, Linux and MAC. GOWrite supports copying diagrams in Sensei's Library format to clipboard. Sensei's library format can be selected from Options->Clipboard graphics.
I have written beginner go-book in Finnish.
In ancient past I wrote book "GO, Jumalten peli" together with Matti Siivola.
Free version(without server provided services) is also available, this is good for beginners.