I am looking for some user script or web service to receive an alert when a question on StackExchange is reopened. I should be able to bookmark which closed question I am interested in. There is no built-in feature in SE allowing such notification as some don't see the point in it.
IFTTT (If This Then That) is a website that lets you connect services and websites together. Each StackExchange post has an RSS feed. Use that as an input to your recipe. You'd have to have separate instances for each page you want to follow, but it would work. Your output could be an e-mail.