MacJournal is a program for creating, modifying, and managing a personal journal.
It can be used for diaries, logs, most anything. And, because it's written using Cocoa in Mac OS X, it supports all the cool OS X doodads you would expect. Things like toolbars, spell checker, font and color panels, localization, and drawers are all utilized to provide you with a useful and consistent interface with that of Mac OS X. Now you can also upload your entries to online blogging services.
v2.6.1 is the latest freeware version of MacJournal.