If you're at home at the command prompt, love your text editor and you eat key commands for breakfast, Holly is the to-do manager for you. Holly sports impressive features, and all of them are accessible via key commands you already know, no sign-up required.
Holly sports impressive features, like projects and nested to-dos, color-coded tagging, and instant cloud syncing, all free, and built behind a simple UI that will feel at home if you spend any time in a text editor. There are hotkeys and key combinations for every feature, so keep your hand off the mouse. You don't even have to sign up to use Holly-just click to get started and the webapp gives you a custom URL that you can return to at any time. You can even share your to-dos with friends or coworkers using the same URL, and they don't have to sign up to see or edit them.
Granted, Holly may not be for everyone, but once you've spent some time with it, you'll find you spend less time fiddling with your list than you do working, which is always a plus.