Give every employee some money to spend on realizing ideas to improve the business. Allow for "pooling" of the money between employees. Make a little competition at the end where all can shortly present what they did with their fund and how it helped their business to get others inspired. It is only a small step, but can be realized in every "classical" business environment. It not only spurs creativity, but also is a strong signal for valuing entrepreneurial behaviou. You can restrict the spending, if you feel necessary (e.g. no office equipment).