google plugin

Flash'in'App lets you easily embed Flash Player.plugin in your Mac application

Recognized as the BEST Photoshop plugin for creating jigsaw puzzle effect.

REALbasic spreadsheet plugin control.

Filemaker plugin for generating charts

Chroma key plugin for Final Cut Studio.

Photoshop plugin for image resizing, Pro version available.

RapidWeaver plugin allows you to blog anywhere.

QT plugin for many media types.

Contextual menu plugin to view DICOM images.

MiniMail is a plugin for Apple's Mail application.