One of the very best tools for managing task overload is to get a grip on prioritizing work into what matters (important) and what's critical (urgent). This prioritization method is from Stephen Covey's classic The 7 Habits of Highly Effective People - it's an oldie but really practically useful.
A simple grid is the best way to visualise this. You can use a white board too.
This is a wonderfully funny youtube clip of the marvellous Harold Taylor demonstrating why the urgent and important style of prioritization and work organization is extremely valuable - stay tuned to the end and you'll see why this is important for not just you but those in your organization too.