The usual CRUD scenario is that you do a DB lookup, then perhaps alter the object, save it to the db, and return to the client. All tasks are performed sequentially. Unless multiple async calls are a common scenario, then I think I'll leave them out. Is there more multiple async examples you can think of?
-Anything dealing with disk I/O like copying or reading files -Sending / receiving from S3 or other file repository -Making a request to external web services as part of a request -Working with document DBs like Mongo where instead of a join you can do one query per table in parallel
I would love it if you could check out asyncblock and see if you like how it helps manage control flow with fibers. It would be easy to integrate with what you have already. We use asyncblock in a very large node based application, and it's really helpful for keeping business logic straightforward and simple.
Another possibility would be using node-sync (https://github.com/0ctave/node-sync) if you prefer their approach.