If you'd like to keep track of new free Logos titles, I've created an RSS feed. It's available here:
http://www.logos4training.com/feeds/freelogosbooks
There's also one for Vyrso books:
http://www.logos4training.com/feeds/freevyrsobooks
You can either put those URLs into your favourite feed reader, or you a service like http://www.feedmyinbox.com/ to get them emailed to you.
