There are a variety of tools, techniques, resources and information available for taking notes. There isn't just an App for that there are literally hundreds. This time we are going to talk about just 4! All of them part of a single service.
Evernote is the service. It lets you take notes and keep track of lists, documents, all kinds of stuff on virtually any device you own. There are apps for the desktop, iOS devices, Android and clippers, plugins, and add-ons for most browsers.
Skitch for Annotations! Skitch lets you take photos and annotate them. These can be anything from screen grabs on an iPhone to massive images on your desktop. Skitch basically lays a transparent layer over your photo and allows text, arrows, shapes and squiggles on top of your image. These annotated images are uploaded into your Evernote account and available in Skitch on all your devices.
Penultimate is a handwriting app. It lets you make simple and complex notes and keeps them all...yup, you guessed it. Right in your EverNote Notebooks.
The last item sort of speaks for itself. It's Contacts management tool.
Three tools and 1 Service that let you remember it all.