This is an interesting combination of Search, DWF and Freewheel to find and render/view DWFs from a link. The only downside is it seems some sites, or maybe older DWF’s, display “not valid”. The actual DWF is fine so suspect fire-walls, or similar, are blocking Freewheel.
What does it do?
DWF-This-Link! bookmarklet converts your DWF file links on your web page to thumbnail preview images (rendered on the fly). Visitors to your web page can click the thumbnail image to view the DWF using the Project Freewheel DWF Viewer.
UPDATE 28–08–2006: Scott explains the Not Valid response