While I like to think I'm a highly organized person, but I am completely scatterbrained due to all the ideas always running through my head. There are a few apps that I use to save my sanity and keep me productive, organized and on task (usually). I've listed my favorites below and how I use them, I'm sure many of them have more features that I don't currently use so feel free to click the links and read up a bit more if it sounds like something that will be useful for you.
My life is only as organized as it is because of Wunderlist. Now, I'm not that organized, but if I didn't use it I would be a royal mess. There is a web based version as well as an app. I always have the web based version open in my browser when I'm online so I can save action items as needed. You can basically sort it into different folders and within those folders you create a check list. You can even add notes or another check list within those check list items. Confused? Check it out. It's a great way to save your to-do list and sort it as needed.
To be honest, I don't use this much right this second. I seem to switch back and forth between Evernote and Wunderlist depending on my preferences and needs at the time. Evernote is great when I want to save entire webpages using the web clipper tool, prewrite a blog post, save files for certain projects, etc. When Wunderlist isn't complex enough, Evernote is my go to. I know I haven't used evernote to it's full potential, but am working on exploring the different features and ways to use it. You can tag things to help you search for them later (example: save recipes, tag the ingredients and search by ingredient when you need it), add different types of notes: regular notes, screenshots, audio, webcam and ink.
This one is new to me and I'm loving it so far. Basically you can track your time doing certain tasks. I tested it out for just a few days using the free version where you can track up to 4 different types of tasks. My tasks were Design, Marley's Mutts, Housework and Unproductive. They have a bunch of fun icons you can use for each type of task and you can color code. You can view a pie chart as well as your totals for the day, week, month or custom date range. I decided to upgrade to the pro version ($2.99) so that I could add different tasks. I also set it up to remind me every 15 minutes while I'm tracking because I tend to turn it on and then forget to change my task when I move on. I love being able to see how I'm spending my time each day.
If you use Google calendar, but are not loving the way it syncs to your iPhone's calendar, get CalenMob. I did upgrade in order to get the "Mini Month" feature where you can see what's happening each day of the month without having to click on each day. Other awesome features are that you can add while not online and it will sync later, you can add recurring events and you can manage and see multiple calendars at once.
I hope you find any (or all!) of these helpful to help you organize your life and keep you productive!