Pownce is a way to keep in touch with and share stuff with your friends. Send people files, links, events, and messages and then chat.
The desktop software makes it even faster to read and send notes to your friends. Features:

• Auto-updates every 60 seconds.
• Alerts you of new notes.
• Send any kind of note.
• Progress bar for sending files.
• Reply to notes super quickly.
• New! Save favorite notes for later.
• New! Manage your friends.
• New! Save custom preferences.

Requires Windows 2000/XP/Vista, and you must have Adobe AIR installed.