Google are always making small unannounced tweaks and improvements to their products—here are a few of the more noteworthy ones we've spotted recently!
Scroll Depth Tracking
I gave out at length last year about the fact that you can't specify the trigger conditions for the listener dropping on the scroll depth trigger—meaning the page length couldn't be calculated accurately and causing scroll depth events to fire early. I suggested that they might want to let you select the listener condition. Lo and behold, they did pretty much exactly what I asked! It also defaults to Window Load which is ideal.
File Extension and Is Outbound
I always teach attendees to my GTM training course how to set up events to detect clicks to download files and clicks on outbound links. That's got easier recently thanks to Google's introduction of file extension and 'is outbound' component types for the auto-event Element URL variable. This allows us to isolate the file extension with very little effort, and can be used in tags and triggers alike. Similarly, the addition of "Is Outbound" allows for quick and easy configuration of outbound click events.
Client ID through the API
This isn't a GTM one—though it will save you a bit of time if you're setting up Simo's Standard Custom Dimensions. Client ID is now queryable as a dimension through the API as standard—and that's backdated for 18 months; meaning going forward you no longer need to worry about setting it as a custom dimension!
