We developed our own internal app overnight tailored to the way we work. We figured the time devoted to organizing our priorities would help us out in the long run.
Our to-do tracking is separated into three lists: monthly, weekly, and daily. At the start of each month we list the items we want to accomplish. Next, at the beginning of each week, we transfer items from our monthly to-do list to our weekly to-do list. Then at the start of each day, we take on tasks from our weekly to-do list and aim to accomplish it by the end of the day. Random tasks will obviously come up so we add it to the appropriate list.
Another advantage to our system is that we're able to see eachothers' lists so everyone is held accountable -- if someone is slacking, we'll tell them. A SMS alert is also sent to the person's phone if their last login is greater than 24 hours.