Would love to hear about others you use. These are all free except Notability.
  1. Trello
    Amazing, visually organized task manager that syncs across all of your devices and desktop and allows you to collaborate with other team members. I've found that the simplicity of the interface allows for endless customization in how you organize your work. I've tried so so many different task managers and Trello rules them all for me.
  2. Google Drive
    If you collaborate at all on Google or use Microsoft Office this is a must. Can't tell you how many times this has saved me when I've needed to quickly access a spreadsheet or word doc on my tablet or phone in a meeting. Incredibly powerful for a free app.
  3. Notability
    When the basic notes app on my phone won't do and I need to add photos, sketches, make audio recordings or share with a team, Notability is awesome. I had to quit taking written notes because I was losing them or having trouble organizing and acting on them and Notability has been a game changer. Worth the $2.99.
  4. AnyList
    You can use this for making literally any list (duh) but we use it for groceries because you can share with family members and stay on top of who has bought what and what's missing from the fridge or pantry. No need for last minute "need anything??" texts from the checkout line. You can also store recipes, a great feature to also help with shopping.
  5. Basecamp
    Similar to Trello, great for project management. Especially great for design threads, perfect visual record of the conversation.
    Suggested by @dev