swfversion.com; find out what version that ancient swf was published to!
The number of times I've experienced producers or website editors asking questions about .swf's published years ago (for which the .fla is often lost) is crazy. Flashmagazine.com published an article yesterday outlining a new service that's launched as a beta; swfversion.com. Using new Flash 10 magic (not the technical term, but you get my drift), it enables anyone with that version of the plug-in to check what version of ActionScript and what player version the .swf was published for. Incredibly useful in dealing with legacy content.