We've mentioned OpenOffice.org a few times when discussing Microsoft Office alternatives, but if you're specifically looking for something that interoperates with Word, there's also Abiword. Until recently, OS X users were stuck with a 1.x build running under X11. But now there's a shiny new Aqua build of 2.1.1 available for testing. AbiWord has a nice tidy interface, and reads and writes files in the formats you'd expect: MS Word, WordPerfect, OpenOffice.org Writer, RTF, etc. Gnu Bob sez, check it out.