I've never used Soulver, because I don't have a Mac. I really liked the idea of using text editor style input for a calculator. Being a software developer, I created one to see how this would work. This is my interpretation of the text editor style calculator and I'm trying to found out where I can take this design.
I think you pick some good points from various websites. I know hierarchical discussions bother me all the time, especially the branching of replies to the right. I'm not sure yet what the right way is to make discussions work, but at the very least they should be linear.