Not a programmer by trade but I mess around with a lot of the Google APIs for fun. I work in a marketing agency (content strategy) and our team supports dozens of clients. One of the biggest bottlenecks is email response time from clients.
I used the API to go through all of the emails we've received from each client and looked for patterns on date/time of send.
Using that data we get much better response rates by sending emails just before the time when the client will likely be working on email (i.e. the email we send is most likely to be at/near the top of their inbox when they sit down to their computer).
I built an application that used Gmail to drive an application to automatically share generated reports with a set of users.
A user would fill out a Google Form, which would send an email to a specific Gmail account when the user submits the form. An automated process would scrape the Gmail account every 5 minutes looking for unread emails containing setup requests. The process would then create a new drive folder and share it with the users specified in the onboarding request. Then, generated reports would be emailed to the same email referencing the newly created folder. The automated process would download the reports, upload them into the shared folder, and send the users who can access the folder an email notifying them that a new set of reports is available.
I had a lot of fun using the Google APIs! I played around with translating the reports into a Google Sheet as well.
I have used the Gmail API in Google Apps Script to calculate my monthly uber credits usage. The company where I work provides fixed uber credits per month and I use the script to calculate how much over / under I am.
I used the API to go through all of the emails we've received from each client and looked for patterns on date/time of send.
Using that data we get much better response rates by sending emails just before the time when the client will likely be working on email (i.e. the email we send is most likely to be at/near the top of their inbox when they sit down to their computer).