I think calling it a "notebook" is a misnomer and takes away from the collaborative and organizational aspects. Notebooks are physical, personal, and the word doesn't symbolize organization or value in my mind (as a once student who has many notebooks scattered about that I never use.)

Something like "agendas" would be more enticing, but I personally would use the headline as an informative statement to what your service does best like "Collect our thoughts" or "Collect and Collaborate."