Recently I wrote about a using a pending folder. A waiting for reply folder is very similar, but is filled with emails you have already completed and need further input from someone else.
A waiting for reply folder is a great folder to have while mobile because you can quickly see what you need to attend to. If you need to request a reply again, you can add the email to Google tasks with a keyboard shortcut.
Another way to utilize a waiting for reply folder is to use a filter in Gmail. If you use a service like Followupthen, you can create a filter to look for the confirmation replies they send to add directly to your waiting for reply folder.
What other simple folders do you use to track your email communications?