I've been using Google Tasks for some time because they're simple and can now be dragged and dropped right in Google Calendar, plus my favorite iDevices app, Calengoo, supports them, plus Gmail integrates them. It's easy to have a list of appointments and tasks together. On top of all that simplicity and free goodness, this post, Max Themes Blog - How to Make a Simple Menubar Task List using Google Tasks & Fluid, has a nice little hack to put Google Tasks in your Mac menubar. Simple. Nice. Pretty.