Kiwi

Kiwi is a full-featured App.net client in a super simple package built just for OS X. Kiwi packs in all the best features of App.net, like private messages, and inline images into a clean, simple, and easy to use app.

• Focused Conversations - Kiwi focuses on the path of the real conversation and moves the chatter to the side.
• Private Messages - App.net is great for private chats too. With Kiwi you'll manage your private messages with ease.
• Twitter Crossposting - Keep your Twitter friends in the loop with Twitter crossposting. Setup up once and forget it.
• Unified Timelines - See all your mentions and followers in a single timeline or keep them separate, it's up to you.

• Choose fonts.
• Disable unused timelines.
• Improved handling of embedded links.
• Improved timeline marker support.
• Many bug fixes and UI improvements.