Subminimal has released TrackPAD, a virtual "Sticky / Post-It" VST plug-in designed for Tracktion (but may work in other VST hosts).
TrackPAD allows you to type any notes (text) and store them with your song. It supports up to 4096 characters, undo/redo, copy/paste, and loads the current Tracktion 2 colour scheme.
Windows and Mac OS X versions are available and the source code is also included.