Microsoft’s office is the ‘standard’ office application, but not something I’m willing to spend money on. On Windows, OpenOffice 2.0 is excellent, and as a user is very similar to MS Office 2000/2003, and has good compatibility with MS’s version.
Open Office
This comes in two under-developed versions on the Mac, one official one that uses XWindows (a *nix windowing environment), and an unofficial one based on Cocoa called NeoOffice.
Read the Mac download page for the info, I’m trying the Neo version first, I’ll see how it goes.
Most other Office applications are platform specific.