The Fien Multi-Master is one of the most effective power scrapers for glue available. It simply vibrates back and forth and can be equipped with a sharp blade, different saw teeth, sanding disks, or carbide grinders. It works wonders for removing glue, removing grout between tiles, and sawing into wood or plaster, and it creates little dust. Multi-Master is a good name for it.
Fien tools are not available in all stores and where it is available they don't carry all the accessories. I like this too so much that I have made it and all the blades available here in my On-Line Store.