First of all: Thanks for the work that has been done for this site. I am a new user, but I have been looking for something like this for a long time!
I have an Idea for a nice little enhancement:
If you choose a chord alternation, it should remember it, so you can print it out with your preferred alternation and store it in your songbook with your favorite chord alternations.
It could be implemented simply by storing a cookie with the song name, and it's alternations. That cookie should be read before rendering the chords, so they will be as the user chose them to be both in print and in the songbook.
Cheers, Anders