For implementing GTD you can use this web-based application:http://www.Gtdagenda.comYou can use it to manage your goals, projects and tasks, set next actions and contexts, use checklists, schedules and a calendar.A mobile version is available too.
I too have found this book very useful. I have purchased many copies for my friends and family for Christmas. I even found a website online that has it in different font sizes for comfortable reading. This website is awesome!http://www.readhowyouwant.net/pcsWebUI/BookDetail.aspx?BookId=13231