In putting this guide together, I focused on native iOS apps/suites that featured all three core office suite applications and were designed with explicit iPad support. However, there are some additional options out there that you might want to consider if you need only specific features or that can expand on some of the apps I've already discussed.
Mariner Calc (http://www.marinersoftware.com/products/calcipad/) is a standalone spreadsheet app for the iPad. It offers a clean interface, range of templates, and supports more than 200 functions, which makes it more versatile in some ways than the other spreadsheet options in office suite[nd]type apps.
Although Mariner Calc isn't likely to be a solution for those who spend their professional lives in Excel, it can meet many of the on-the-road needs of home users and small businesses (and will be particularly attractive to users of Mariner Calc for Mac).
Mariner Calc lacks any cloud service support, but does support Excel and .csv files. Although basic, its $.99 price tag makes it an attractive option for those with modest needs.
Along the lines of Mariner Calc, Plaintext (http://itunes.apple.com/us/app/plaintext-dropbox-text-editing/id391254385?mt=8) is a basic text editor. While it doesn't support formatting in the way other apps/suites do, Plaintext is designed with one goal: to help you write and avoid distraction.
The app includes Dropbox sync as well as on-device storage. The interface is dead simple: just a list of files (use of folders is supported but options), a search option, and a space to write.
Although it isn't for everyone or every situation, it meets its goal brilliantly and you can't beat the price because it's free.
Split Pea (http://www.splitpeaapp.com/) is another text editor, but with an interesting twist: It includes a web browser. When most of us are working with a text or word processing document on a computer, we often switch to a web browser to look up information, verify facts, or even just take a brief break (all of which I've been doing as I've been writing this article). The problem with writing on the iPad is that switching between two apps is never as seamless as switching between two windows on a PC or Mac.
Split Pea solves that problem by dividing the screen in half (either horizontally or vertically depending on your iPad's orientation). The upper or left pane displays a webkit-based browser that supports bookmarks and tabbed browsing; the lower or right pane displays a clean and simple text editor that can create or edit documents.
The text editor also supports tabs so that you can have multiple documents open at once and supports printing via Apple's AirPrint.
As of this writing, one downside is that only iTunes-based file transfer or email sharing is supported (Dropbox support is planned for a future release). Still, if you create text content based on online reference sources, Split Pea is a must-have app and well worth the $3.99 price tag.
Dragon Dictation (http://www.nuancemobilelife.com/apple/dictation.html) is a free app from Nuance (makers of Dragon Naturally Speaking) that, as you might guess, uses speech recognition to type words as you speak them. The app relies on access to Dragon's servers, meaning network access (Wi-Fi/3G/EDGE) is required.
Dragon supports transcription to files, but can also be used to copy and paste spoken words into text or email messages, or into any app that supports text input. If you find typing on your iPad a bit too limiting, Dragon Dictation is definitely worth a go.
Nuance also produces a version specifically designed for doctors and healthcare professionals (http://www.nuance.com/for-healthcare/by-solutions/mobile/dragon-medical-mobile-dictation/index.htm) that recognizes medical and related terms.
Google Docs obviously isn't an iOS app in itself. In fact, almost all the apps/suites I've listed offer Google Docs as one of the cloud-based services that they support.
However, Google does support (http://googledocs.blogspot.com/2010/12/tips-tricks-more-options-for-mobile.html) access and editing of documents using its traditional web-based interface using Safari on the iPad.
While a native app has a number of advantages, the free nature of Google Docs and its capability to support real-time editing by multiple users can make it a compelling solution in its own right.
If you (and people in your organization) are heavy Google Docs users already, you may want to try using the standard website as opposed to a dedicated app. This may be a particularly attractive option if you routinely use an iPad provided by your school or office that doesn't allow you to install additional apps or if you share an iPad with others (family members, coworkers, classmates) and don't want to have your account information or documents accessible to others.
You can even use Safari's "add to homescreen" feature to create an icon for the Google Docs site on your iPad's homescreen for easy access.