I would ensure that I was empowered to use company resources to offer an extra paid personal day in exchange for the unpaid overtime. (I'm taking the liberty of assuming that your team is salaried and not hourly). But my management style would have already set the stage for my team to put in the OT to get the job done without me having devised a way to motivate them. I've always strived to give little perks for the "extra mile" a team member/employee has gone for me - a little gift card to a restaurant that I know he/she enjoys, or ITunes, Home Depot, - Sending everyone home a few hours early to get a jump on a long weekend. I've also kept track of the "extra miles" in their personnel file and am sure to discuss again during their annual reviews for promotions/raises. Additionally there are Certificates of Appreciation that can be hung on their office walls/cubicles and permanently entered into their employment record. I’ve also ensured that all praises back from the clients are shared with my team and when possible ask the client to address the “Thank you” letter to the entire team. So most of the time my teams are pretty happy to put up with my demanding meticulous requests to complete last minute timely projects.