The application I am using the most on my iPad is Evernote. Very handy to take notes during meetings and sharing those with my other devices through the Cloud.With the Free version you can store all kinds of notes, eg cut and paste pieces of text from a webpage into a note. Everything you capture will be automatically processed, indexed and made searchable. If you prefer, you can add keywords or organize notes in different notebooks. You can also attach images, audio and PDF files to a note.
In the Premium version you are not limited to PDF, but you can attach all kinds of files to your notes. Also in the Premium version the notes database is stored locally on the iPhone and iPhone and you can work with Evernote without web access, very usefull on the airplane.