If I'm running a small minyan that sometimes has a quorum and sometimes doesn't, and I'd like to only hold the minyan when I know we'll have ten, is there an online tool to help me manage this?
http://www.minyanman.co.za/ is a Minyan management tool.
Minyan Manager is a community service to help people manage business minyanim. We know how useful it is having a mincha minyan at work but how time consuming it is to manage it, as well as how frustrating when people come and yet a minyan is not present. We hope this will reduce the administration and encourage more companies to have a mincha minyan. For more information contact firstname.lastname@example.org
JPal should solve this issue.
Please check this thread on SE: Davening with a Minyan in China
Minyan On Demand let's you create a minyan anywhere in the world and instantly have thousands of users notified. Ideal for international business travels and anyone looking to pray with a minyan where there's no permanent minyan available.
https://synago.io does this:
This is Synago. Automagic minyan planning and scheduling of synagogue services in the diaspora.
http://www.doodle.com/ is a good resource for organizing peoples' schedules