A little bit of healthy competition can go a long way to boost employee drive and productivity, especially when there are prizes involved. Try dividing departments into teams and have each employee set weekly or monthly goals that are more difficult to complete than a simple daily to-do list.
By setting goals that are challenging yet still achievable, employees will push themselves to go above and beyond their normal workload. But of course, there has to be a prize for the winning team. Use perks like a free lunch or cash prize split amongst the team members to incentivize the next round of competition. Be sure to make this a regular occurrence in the office instead of a sporadic event, this way employees will constantly be striving to produce their best quality work.