Here is a list of applications people mentioned in this thread, for computer, iPad, or iPhone. And a few I added.
Mac OS X (no Windows version):
-- iWork, $79.00, productivity suite, includes Pages, Numbers, Keynote. Or these can be purchased separately through Apple's App Store at $19.95 each for direct download to Mac.
http://store.apple.com/us/product/MB942/iWork-09
-- VMware Fusion, $49.99, emulation, to run Windows applications on Mac. (Different vmWare products are available for Windows and Linux platforms.) As an emulation it may run slower than a solution such as Bootcamp with Windows. But it allows running Mac and PC applications simultaneously.
http://www.vmware.com/products/fusion/overview.html
-- Bootcamp, free, comes with new Mac, allows installation of separately purchased Windows operating system (Windows XP, Vista, or 7) in a separate partition. This is not a Windows emulation so it's probably faster than emulators such as VMware Fusion. With this solution, switching from one OS to the other requires shutting down, choosing the other OS, then restarting. Windows and Mac applications cannot be run simultaneously.
-- Chronicle, $14.95 from application site, or $9.99 from Mac App Store. Financial, bill management. Application site:
http://www.chronicleapp.com/
Mac OS X (also available in Windows version):
-- Open Office, free, productivity suite.
http://www.openoffice.org/product/index.html
-- Microsoft Office for Mac Home & Student 2011, $149.99, productivity suite. Includes Word, Excel, Powerpoint, Outlook. Note that iWork or Open Office provide most of the same functionality (other than eMail) cheaper or free. I was wrong when I previously said Outlook (eMail) doesn't come with MS Office for Mac.
http://www.microsoft.com/mac
-- ESET Cybersecurity for Mac, $59.99 for 2 years. I like this much better than Norton. Had trouble with Norton, never with ESET. Includes antivirus and anti-spyware protection.
http://go.eset.com/us/store/
-- Free antivirus software. I've noticed that the free ones may be partial protection, often with more comprehensive packages also sold by the same company. I haven't used these or researched them in detail. Mentions were: iAntivirus (Mac only), Avast, and Sophos.
-- Evernote, free, notes and projects.
http://evernote.com/
-- Calibre, free (donate), eBook management and conversion. Includes eBook reader for ePub formats, which also translates various other formats into ePub for viewing purposes. Calibre can also convert between various formats.
http://www.calibre-ebook.com
-- Acrobat X Pro Student and Teacher Edition for Mac, $119. The student edition is much cheaper than the non-student edition, if you want or need an application to edit PDF format documents or books, where those PDFs are not locked against editing. Available $111.99 at Amazon (on DVD).
Adobe:
http://www.adobe.com/products/acrobatpro.edu.html
Amazon:
http://www.amazon.com/Adobe-Acrobat-...+x+pro+for+mac
-- Adobe Reader X, free, PDF reader.
http://get.adobe.com/reader/
-- Adobe Digital Editions, free, ePub format eBook reader also good for reading ePub eBooks borrowed from a library.
http://www.adobe.com/ap/products/digitaleditions/
-- Kindle for Mac, free, Amazon formats reader (azw, azw3, azw4, Mobi).
http://www.amazon.com/gp/feature.htm...cId=1000493771
-- Kindle Previewer, free, Mobi format eBook reader, Amazon.
http://www.amazon.com/gp/feature.html/?docId=1000765261
iPad or iPhone:
-- Evernote, free, notes and projects.
http://evernote.com/
-- Kindle for iPad/iPhone, free, Amazon formats reader (azw, azw3, azw4, Mobi).
http://www.amazon.com/gp/feature.htm...cId=1000493771
-- BlueFire Reader, free, ePub and PDF format eBook reader, iTunes store.
-- MegaReader, $1.99, ePub format eBook reader, iTunes store.
-- GoodReader, $4.99, robust PDF format eBook reader, iTunes store.
-- Pages, Numbers, & Keynote, $9.99 each, iTunes store.
Multi-platform, Various Computers and Devices:
-- Cloud storage, syncing, file hosting, backup services. Many venders offer 3 to 5 GB of free storage space, and some have various syncing options. As one possible example, the user could keep music files in the cloud, then listen to a tune by streaming it direct from cloud to mobile device, without having to actually store it on the mobile device. There are many venders, many associated applications. For more information and comparison charts, see:
http://en.wikipedia.org/wiki/Cloud_storage
http://en.wikipedia.org/wiki/Compari...ation_software
http://en.wikipedia.org/wiki/Compari...sting_services
http://en.wikipedia.org/wiki/Compari...ackup_services
-- Some specific examples of above: Dropbox, SugarSync, Amazon Cloud, iCloud, Mozy, CrashPlan.