This is actually the very reason behind a side project & successful Kickstarter I've been working on called Taco (http://tacoapp.com). Taco essentially aggregates all of my tasks across multiple task services (Asana, Basecamp, GitHub Issues, Trello, Starred GMail Emails, + ~40 others) and puts them on a single screen. This effectively allows me to prioritize across my entire life rather than within a single project. The added benefit is that it helps me stay focused throughout the day since I'm not switching between apps. At the end of each day, I just set aside the tasks I want to work on for the next day - very similar to what Jeff is suggesting here.