AS3 Code Highlighter
A few days ago I found this, but the only downside was that it didn't offer AS3 support. So, I went ahead and made one for them. I opened up the “AsColorSyntax_3.xml" file located in the Configuration/ActionsPanel/ActionScript_3 folder, did a simple for loop to add the appropriate items, and voila! Done :) You can download the .zip file here.