I am a sucker for text editors and in a similar vein, I am a sucker for task managers. I can't help myself from trying them out.
Wunderlist looks kind of interesting but I'll need a lot to persuade me to move wholesale from Remember The Milk.
And then today I saw Taskwarrior "a command-line todo list manager". Wow, that appeals to my inner geek. It is available as a binary for most flavours of Linux, there's a graphical front-end, it's easy to use but with lots of extra oomph. And you can set it up to use Getting Things Done (amongst other methodologies).
Definitely one to keep an eye on.