The much admired (and much maligned) Stanley #55 universal plane. The planing mill in itself. This, for me, was THE tool. It is the epitome of Victorian tool engineering and I think it is the bee's knees. It can do everything. When I bought it from the Merchant of Ashby, (he made me promise not to hate him for it afterwards), I set it on my bench and shouted, "MAKEAMAPLECOFFEETABLE!" I came back later and sure enough, it had made a very nice coffee table all by itself. I don't trust it do that often because this is a hobby for ME, not my oldtools, and besides, the plane is too partial to an ugly polyurethane finish instead of shellac or oil. Thank you for the magical plane, Mr. Leach.
This guy weighs upwards of 14 pounds when all decked out in fences and stops, and it takes forever to set up, but it can cut serviceable moldings, rabbets, dados and the like without investing in dozens of dedicated wooden planes. I find it fun to set up and I'm not in a hurry to stick moldings at an eighteenth century production shop. I can take my time and tune this combination plane as I need it. Reproductions of the original instruction booklet are widely available, and I learned a lot about it's workings from the Museum of Woodworking Tools.
It came with 52 little cutters (a molding cutter is pictured to the left of the plane) but you could special order 41 more.