On top of my list is Wunderlist. The todo app of my choice. I am using Wunderlist since one of the first versions. I tested some alternatives from time to time, but I always got back to Wunderlist.
Wunderlist is free and comes with a advanced pro version with some more functionality. Which become interessting if you are working in a team.
I am using Wunderlist to plan everything. My website, my jobs, things like the WordPress-Workshop I do and even private things. I, for example, do have a list with places I want to visit.
Wunderlist is available on all common platforms.
If you don't like Wunderlist, you should take a look at ToDoIst. The todo app comes with a similar functionality as Wunderlist. The free version is a bit more limited as Wunderlist. ToDoIst has got a very minimal design, which I like a lot.
ToDoIst is available on many platforms.
Whatever I do, I'm tracking time. Toggl is always running. When I write a blogpost, work on a website or are on the phone. Time tracking is always on. Toggle somes with a nice overview of the tracked time and has a great set of features in the free edition.
If you would like to know, where your time goes. Try toggl.
I am using Sunrise to manage my dates. It depends on a Google-Calendard. I would like to recommend it, but is was bought by Microsoft some weeks ago. It will be integrated into Outlook, unfortunately.
Google Apps for Work
I use Google a lot. So I registered a Google-Apps-Account. Which currently costs 40 Euros. This way I do have access to many known Google-Tools using my own Domain. I am mainly using the calendar and google-drive.
I really like using mindmaps. I like to sketch on paper. But when mindmaps become more complex and I want to change things a lot, I use Scapple. Scapple is a MindMap app running under OS X and Windows and costs 15 Dollar.