At the risk of making your service/site appear error-prone, you could make it evident on each page what a user should do if there is a problem. Basically have a

At the risk of making your service/site appear error-prone, you could make it evident on each page what a user should do if there is a problem. Basically have a method for the user to send an email to support with what is equivalent to a stack trace for that page: include their browser info, and any other relevant generic info. Just spit-balling here.