Having worked in several companies I've seen a lot of effort put into boosting creativity inside the company. People regard themselves as not being that creative and for that reason design-agencies are being contacted to organise a creativity session or people start hooking up with universities to get fresh ideas. From my experience however I never saw the lack of creativity to be the real problem in any of the companies. If you talk to people you'll find that they are actually quite creative at home, working on a project during small evening hours or working on a small project with a friend. However at work, they don't always show the same passion and creativity.
So what makes working at home so different than working in the office? I think one of the reasons is the lack of stimulus in the office. Make people work closer together improves interaction and will improve communication between problem-identifying people and problem-solving people. Buy interesting technologies, products and magazines that you like everyone to work/think more on. They act as triggers for everyone to use that technology, material, etc. Finally put all ideas on a wall for everyone to see (or make a list of ideas and put it in a coffeecorner). This boosts discussion about ideas and helps to sharpen the idea itself or triggers other people to create there own ideas as well.
Another difference between home and work: money, time and freedom. It might seem that companies have enough resources to work out several ideas, however most of the time wasting resources is not very appreciated and thus ideas are not picked up. Give people time to work on their own projects. Quite likely not everyone will be using this free time so in practice little resources are wasted, but the people who do, will be enough to create some buzz in your company.
Help, don't manage. There is a lot of easy accessible knowhow available in any company and this is a great benefit over a DIY-project at home. Use these freely available resources to bring the ideas to a more mature stage: ask a mechanical engineer to review the idea, ask a designer to help with some renderings, etc.
If you want a bit more direction in this fuzzyness, try thinking about implementing a reward system. This way, everyone is asked for specific deliverables, avoiding the creative process itself to be managed what can lead to frustrations. After reviewing, the project gets rewarded by freeing resources for maturing the idea further. This is similar to how design-competitions work (not the process but the final results are judged).
These four easy guidelines (adding stimulus, providing resources and help and introducing a reward system) help every company to make creativity flow continuously rather than at defined moments and requires little effort and management. These guidelines don't replace scheduled creativity sessions where specific issues are targeted and require a specific creativity process.