The best presentation software for the iPad Keynote. Apple's presentation app is simply amazing. You can create beautiful presentations with sophisticated transitions and animation effects, as well as draw on capable text and object formatting tools. There's also a presenter notes feature, and you can add graphics from the Photos app, as well as create charts, tables, and shapes. Chances are you won't miss PowerPoint if you're using Keynote. My only frustration with it (besides the lack of Save As across all iWork apps) is that it displays only in landscape orientation -- a real puzzler, given Apple's other iWork and native iPad apps are orientation-adjusting.
Quickoffice. The Quickoffice suite cannot view, edit, or create presentations.
DocsToGo. The DocsToGo suite lets you open PowerPoint presentations and add notes to them, such as to make comments or provide feedback to your spreadsheet jockey.
It also has basic editing capabilities. You can edit the text in your slides, though to do so you must switch to outline mode. Furthermore, you can do no formatting. You can also create blank slides and duplicate or delete existing ones. Note that if you're in outline mode, you have to go back to slide preview mode to insert a new slide. You can't delete or duplicate slides when in outline view.
The result is that DocsToGo is fine for touchup work on existing presentations or to create a basic text-only presentation that you might use as the starting point for a slideshow you add images and formatting to on the desktop -- but that's all.
The verdict: The only real choice is Keynote. It's easily the strongest of the three iWork apps, able to replace PowerPoint completely for many users.
The best PDF markup program for the iPad There are dozens of apps to open PDF documents on the iPad, but the built-in Preview app does that for mail attachments, and most Wi-Fi file-sharing apps preview PDF documents. What you really want is a program that can mark up PDF files, adding sticky notes and the like.
That app is GoodReader ($2). You can do most of the markup you would in Adobe Reader, such as notes, highlights, and even free-form shapes (for example, to circle an item). Once you get the hang of using your finger like a mouse for such actions, it's an easy-to-handle app.
GoodReader is not just a PDF markup app. It can also view Office files, text files, and pictures, as well as play audio files. In addition, it comes with a Wi-Fi file-sharing capability to transfer documents to your computer.