I just discovered that I can use the drawing feature to allow my clients to sign forms on my touch-screen. This streamlines my job so much!
For those who haven't discovered drawing, just create a tiddler and choose .jpg, .gif or any other image file type. You will get a blank box that you can draw in. To change the color from default yellow, create a tiddler titled $:/config/BitmapEditor/Colour , choose application/json as the Type, and type in your color number, such as #000 (black). You can insert this image into your document tiddler using [limg[signatureTiddlerName]], and then when you have the sign the image tiddler, it will show up in the document. From there you can export it or paste it into a word document, whatever.
Every time I think I've exhausted all I can from tiddlywiki, I discover something new. This is a great program!