I see via Murderati that there is a "Shakespearean Insult Kit" comprising words the Bard employed. I rather enjoy Bardic vitriol. I once rehearsed in King Lear as Goneril and was joyously enabled to scream "milk-liver'd man!" at my husband on stage.
As a theatre director Ngaio Marsh must have taught many young actors to handle Will's bad language. She has fun with some of her playwright characters in various novels, particularly Dr Rutherford who scorns someone by pronouncing, "Get you gone, you dwarf - you minimus of hindr'ing knot-grass made, you bead, you acorn."
Myself, I'd be tempted to add the good old Midlands word "orts" that has been out of use now for three generations. Shakespeare used it in the phrase "abjects, orts and imitations" - things thrown aside as of no use, waste, or bad copies. The phrase has been misinterpreted as "objects, arts and imitations" but I know the word "orts" existed because my grandad used to say when you left food on your plate, "eat it up, I don't want your orts." It would combine well with some of our Cumbrian insults, I think. "Thou's nobbut an ort. Waste of a good skin."
Mind you in Cumbria we have a great many placenames and hill names that could be used as insults. Zoe Sharp suggested "Eeh, you great wet sleddle." To that I'd like to add, "E's nobbut a Subberthwaite," and "Thou's a Great Cockup."
More on names another time. I have to go now, I'm feeling a bit Witherslack.