I've been thinking about an app that would be really useful to have.
A plugin that allows you to set certain times of day during which time, certain modifications of any G-Code being run would be applied.
So for example, you could set it to reduce all print speed below 30mm/s between 11pm and 8am so the printer runs quieter when people are trying to sleep.
Unfortunately I don't have the knowledge to produce my own plugins but if anyone's up to the challenge it would be a great feature for the OctoPrint community.