
Awesome Note
Powerful note-taking and organizer app, with colorful themes. Backs up your notes to Google Docs. Create folders, include calendar view in every folder, set up tasks lists, attach photos and maps to your notes, set alarms, set passcode lock for privacy, and many more "awesome" features. iPhone/Touch or iPad app. Free and paid versions available.

Evernote
Evernote makes it easy to capture anything in multiple formats. Input by photo, text, screenshot, audio recording. Tag your notes, organize into notebooks, share with others or keep them private. Save notes to your Evernote.com account on the web and access from any computer or mobile device. Universal app.
Available for Android, iOS, & all major mobile platforms. Free.

Penultimate
Use your finger or a special stylus to draw, write in your own handwriting, and sketch. Create notebooks for each project, turn on "wrist protection" so the touchscreen doesn't draw by mistake when your wrist touches the sreen. Use a VGA adaptor to plug your iPad into a screen display and show your audience your drawing in real time. Import/export your notebooks and more. iPad only.

GoodReader
Super-robust PDF reader with advanced reading, annotating, markup and highlighting capabilities, excellent file manager, text file reader and editor, audio/video player, Safari-like viewer for MS Office and iWorks files. Syncs with Google Docs, MobileMe, Dropbox and more. Create your own hierarchy of folders to save your documents into. Highly recommended for reading & annotating scholarly articles.
Reeder
Read Google Reader RSS feeds on a simple and attractive interface on the iPhone or iPad. Scroll through items one-by-one, or swipe items to skip. Star items for reading later.
Feedly
Similar to Reeder, Feedly is a fun, stylish way to read and share the content of your favorite websites, feeds, & social networks. For iOS &
Android.