Auto increase disk size
Auto increasing disk size to a specified threshold would help to not use resources beyond what is required by an application at a given time.
It would be cool to have a configurable amount of when to actually increase the disk storage. For example, if a 5GB disk is becomes within 90% of being full, automatically add another 1 GB. Or maybe it could be configured by the amount of free space remaining on the disk.
Something similar to how AWS RDS databases can have a starting size but scale up to a specified size.