Mozilla’s authoritative plugin docs

What plugins are you using?

Firefox on MacOSX

Default Plug-in
Java Embedding Plugin 0.9.6.2
QuickTime Plug-in 7.2
Google Update One-Click Installer Plugin
Verified Download Plugin
Shockwave Flash

Safari on MacOSX

Google Update One-Click Installer Plugin
iPhotoPhotocast
Quartz Composer Plug-In
Verified Download Plugin
Java Plug-in for Cocoa
Shockwave Flash
QuickTime Plug-in 7.2
QuickTime Plug-In 7.2

Plugin deployment

Webkit

/Library/Internet Plug-ins

NPAPI

Has the plugin spec changed?

See the Platform Compat list