iPodMemo is a useful Carbon app which will allow you to type up and sync notes or memos to your iPod's Contacts directory.
This is the first public beta but it should work fine on both OS9 and OSX.
Many more advanced features are on the way for v0.3.
The main purpose of this beta release is to gather feedback for the upcoming updates.
You can download iPodMemo at: Versiontracker.com