a slightly modification of Link Warning by Stupid Head@userstyles.

It will use no "moz-icon://"-protocol and thus works in linux also.
I also added a hover effect so the icons are only shown when moving the cursor above the link.

I used the icons from the Crystal SVG Icon Pack by everaldo ( http://www.everaldo.com/crystal.html )

Update 4 (Oct 17, 2007):
- added external text links from a wiki (such as wikipedia.org) to the new window warning alert.

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Update:
- Added some filetypes in Audio and Video: .asf, .ra, .rm, .ogg, .ogm
Update2:
- added Warning for Javascript-Links and Links with ONCLICK-Attribute
- now the mouse cursor will change to the icon so the links don't
flicker around anymore.
- disabled red color style for pdf-links.

Update3:
-added Icon for "linkified" links (Linkification can be found here: http://yellow5.us/firefox/linkification/ )
-added Google Search Result Links target (target="nw