Evernote is an easy-to-use, free app. It lets you create docunments, take notes, capture photos, create to-do lists, record voice reminders, etc. Free iTunes Store..
Pages is a full word processor software tool on the iPad, iPhone, iPod. $9.99 iTunes Store.
Write notes, sketch ideas, annotate PDFs, fill forms, sign contracts, teach a class, make a presentation, keep a journal. $5.99 iTunes Store.
Screen Capture Apps
Explain Everything is an easy-to-use design, screencasting, and interactive whiteboard tool that lets you annotate, animate, narrate, import, and export almost anything to and from almost anywhere. $2.69 iTunes Store.
Keynote is a powerful presentation app for a mobile device. It’s built from the ground up exclusively for iPad, iPhone, and iPod touch. Keynote works through iCloud, so you'll stay up-to-date across all Apple devices. $9.99 iTunes Store.
Haiku Deck has all the features you’ve come to expect from a traditional presentation tool — such as creating in-house graphs, free themes, import access from Dropbox, Facebook, etc. Free iTunes Store..
Prezi designs and creates presentation software. The app allows you to view, edit and present your prezis. Free iTunes Store..
Audio Recording Apps
AudioNote - Notepad and Voice Recorder
AudioNote combines the functionality of a notepad and voice recorder to create a powerful tool to record notes and audio synced with the note taking. $4.49 iTunes Store.