Setting up an online calendar of events is trivial. Creating a mailing list is also simple (but has some privacy issues). But once one gets into "tracking", and especially any monetary issues like dues (even if indirect) one can quickly get involved in state and national laws about privacy, security, and finance even inadvertently and through no fault of your own, if one is not careful to keep it very "generic". And the rules get tighter and tighter all the time. Not recommended for the DIYer (especially regarding security storing private data (every server is going to be under attack at some point), and finance law)....
Quite frankly, my company long ago outsources all private data and fiscal tracking issues to another company, because we do not want to deal with the headaches.