Thanks for your response Joe.

I think limiting the facility to logged on users would be fine as it would effectively be a members area facility. Outsiders could be catered for as members guests.

I think a lot of not for profit organisations organise events that require people to express an interest but are limited in numbers that can be catered for, so a selection has to be made as to who can go.

This coupled with people who change their mind about attending can be a nightmare for organisers, so a simple mechanism that allows people to subscribe or unsubscribe from an interested or selected list and keeps an organiser notified would be good for many organisations who try to organise regular events for members

As you say, an option for costs to be included would be useful.

Regards

Bryn