Drop Box: Stop carrying thumb drives from home to work or computer to computer. Creat a Drop Box account and install it on the computers, phones, and tablets you use most. Any documents you save to your Drop Box file will be synced on all your devices. It's easy and you can start for free with 2BG of storage.
Favorite Use: I keep all of my PowerPoint presentations in Drop Box. I can then access any teaching, anywhere that I am. If a teacher doesn't show up for Adult Confirmation class and I have ever tought the night's topic before, I am ready to go and at least meake it look like I know what I am doing.
Evernote: This app will pick up where your memory leaves off. Snap pictures, take notes, record voice memos. All are searchable and can be organized into folders, tasks, or topics. This is the must have tool for keeping track of pretty much everything.
Favorite Use: When someone brings an original certificate (say to RCIA class) and I only need a copy, I snap a photo with Evernote. It can instantly be put in a folder, accessed in my office, and is searchable. No need to go make copies and try to get originals back to their owners.
ToonDoo.com: Make cool and easy cartoon strips, like the one at the top of this page. Basic account is free. They charge for extra features.