Thought box

Publish the idea of ​​the cycle - "Try it in your office"
Put a box in a visible place in your office like the one shown above. In this box, all employees can throw their ideas on improving, optimizing workflow or something like that. And then with a given frequency to make a public seizure of these very ideas and take them to the collective discussion and revision.
For useful thoughts, you can also assign bonuses, or in some other way stimulate the thought process in the minds of your employees.

As practice shows, it works. And often different employees have brilliant thoughts.

PS In general, in my opinion in any office - must have, along with a coffee machine or kettle.

UPD. Comrade Ermak made a similar, but more it’s solution in the comments - on the organization’s intranet, make a site to receive any offers and innovations. Proposals can be submitted both anonymously and personally, they can be discussed and evaluated.