Want to highlight text, clip a video, or select a section of an image? This module is CCK nodereference on steroids. Annotation Field references not just a node, but a specific revision, field, and intra-field information (like a portion of text).
AnnotationField, itself, is the framework for Annotator field modules to annotate specific field types. Included in this module are three sub-modules:
/videoannotation (currently clips youtube videos with the emfield module)
/imageannotation (currently allows box selection of images from the image module)
/textannotation (currently works on the Body field of a node and CCK text fields)