Back when I was in school, when we Protestants wanted to know a little more about what the medieval background for the Reformation, we were went to the W/JKP Library of Christian Classics which had a few volumes of original sources with introductions. One of those volumes was on Thomas, who after a somewhat rocky start, became the standard theologian of the Roman Catholic Church.
To my surprise, this volume was on CCEL. Yes, the full Summa is available in Logos, but having an alternate translation of a work can sometimes be helpful. In addition, having a shorter work will give some people a place to start.
I have tagged this with the Summa datatype, generally down to the article level. The first few articles go to the next level, but since most links that I have seen are only to the article, I saved myself some work. I have also created a fair number of links, both to pop around the text, as well as to some older works Thomas cites. Of course, more could be added, but I felt that it is useful where it is.
I have not included the indexes at the end of the work. I figure Logos is creates its own indexes... 
SDG
Ken McGuire