Day One is a journaling app for OS X that allows you to write entries, add photos, tag locations, and categorize your entries.
Beautiful, streamlined design: Day One is extremely intuitive from the start, with an interface that is crisp and modern. Writing an entry is similar to posting on Web services like Tumblr and WordPress. The sidebar icons are clear and scale well for Retina displays, and aside from a couple action items, Day One makes most writing options color-neutral to keep you focused on writing.
Cross-platform support: iPhone and iPad owners can also buy and use Day One with more or less the same interface and layout. The design works for both mobile and desktop form factors. Day One also supports entry syncing via iCloud.
Price: It's not a low price, and for the sporadic writer, Day One may not be cost-effective. But frequent journalers will find $10 a small price to pay for such a premium writing experience.
Day One solves the two biggest obstacles to journal writing: distractions and lack of motivation. The $10 price might deter casual users, but for the more invested, it's one of the best tools available for recording priceless thoughts and memories.