I saw several stacks of discarded holiday trees sitting while walking by several alleyways in my neighborhood tonight. Before you haul your tree to the garbage, think about a city-spondored opportunity to put your tree to good use this Saturday by participating in the "Turn Green into Blue" events at several city parks, where you can receive your choice of blue bags, a reuseable water bottle, or compact fluorescent bulbs in exchange for the tree (or a bag of recyclables).