Change Printer v1.0 by Arthur J. Dahm III (Dated January 5th,1987) is a GEOS desk accessory that lets you change your active printer from within another application like geoWrite.

Envelope v1.0 for GEOS and the Commodore 64 / 128 by Spike Dethman (Dated May 13th, 1993) - Neat little desk accessory that lets you print out an envelope.  Can pull data from a text scrap, or you can type the address in yourself. 

Works in GEOS on the C64 and 128 in either 40 or 80 column mode.  Includes full Docs.

GEOS Calendar v1.1 by Richard A. Rardin (Released 7/6/1988) - This is a cool desk accessory that lets you put reminders on a calendar that can later be recalled during another session.  Being as it's a desk accessory, you should be able to launch this while using something like geoWrite.

Font Swap for GEOS by Payton W. Snider II is a desk accessory that works while using geoWrite 2.1, allowing you to swap out the fonts that are available while you're writing a document.

Font Swap can also be found on geoWorld Disk #5 which was released with geoWorld Issue #22.