No, there's no legal way to get Microsoft Office for free. That would be pirating.
There is however, an overall superior product from Apple called the iWork suite. It consists of three programs: Pages, Numbers and Keynote. I'll bet you can guess what each of them do.
http://www.apple.com/iwork/
(check out the video tutorials as well)
I find Pages and Keynote to be WAAAAAY better than their MS Office equivalents, but they are quite different. Numbers is beautiful but a bit TOO radical a change for people who use Excel, so I continue to give the edge to Excel on that point, but Numbers IS the only program I've ever used that made me happy to work with spreadsheets, which I normally loathe.
There's also several free (as in no-cost) Office-type suites: OpenOffice, LibreOffice, etc. Having recently tried them, I liked LibreOffice the best personally, but compared to iWork they look like Cinderella's ugly stepsisters.
The iWork programs are available for $80 for the set (physical DVD) in stores, or $20 each from the Mac App Store. They will integrated into the forthcoming iCloud service as well, increasing their value IMO. Good deal, and getting better. Apple's web site may still have a free trial of iWork, give it a spin. Apple also makes iOS versions of the iWork apps available (not quite as powerful, but they do the job).