XTRAs (plug-in's for Director)

XTRAs add media handling, specialized coding features, and external device communication capabilities to Director. (Note that XTRAs which worked in Director 10 (MX2004) and earlier may not yet have been updated by their authors for Director 11. )

Dean Utian's list of available Xtras is the most current...
The Great Director Mile High List of Products
It includes the updated status of compatibility with Director 11. The XTRAs below are among those with Dir11 versions recently:

3DPI
Property inspector on steroids, for working with 3D. You can create and modify many essential resources directly in this tool. Essential!

Buddy API
Get and set many OS properties including file access, fonts, registry settings, and version info.

asFFT Xtra by Antoine Schmitt
Powerful real-time sound input analysis.

Tabuleiro
Mpeg, Audio, Database, and Web XTRAs.

Xtrasy
Another, very current, searchable directory of available XTRAs.

These others are still viable for previous versions of Director...

SerialXTRA at PhysicalBits

Zeus Productions.
Launching, printing, and AppleScript Xtras.

Amplitude Xtra.
Analyzes sounds playing from castmembers.

TrackThemColorsPro Xtra by Daniel Rozin.
Video input processing tools.

Scirius SetMouse Xtra and others.
Video input processing tools.

Print-O-Matic Xtra.
Excellent control of all aspects of printing content from Director including detailed formatting.

DirectXtras.
Sells a variety of powerful xtras.

Midi-IO Xtra
For Windows and PPC Macs.