After trying to find a software to do online booking for a volunteer sign up system, I finally found the solution! Seminar is so easy to set up, and very functional. I think it is the best.

The improvements I would like to see are Allow Printing View to include all the user input information; or allow to link to categories directly by module or other settings in the front or even just back end.
the cvs export loses the format, so it is hard to use.

but even without these features, I still vote it a 5 star. Thank you for the great work!