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.

geoTheo v1.1 - "A concise thesaurus for GEOS", by Bret M. Timmins (NewSpeak Software).  The following is a quote from the manual:

Welcome to geoTheo. The first thesaurus written specifically for the GEOS environment. Unlike a traditional thesaurus in book format, where precious time is wasted thumbing through a long index, geoTheo gives you nearly instant access to thousands of the most commonly used--and misused -- synonyms by simply typing a word.

Thanks to Bruce Thomas for sending over this neat GEOS Desk Accessory that works in both GEOS 64 and GEOS 128 (40 or 80 column mode).  geoTheo was announced in the August 1991 issue of RUN magazine and Bruce purchased a copy in November 1991.  In September of 2004 Bruce contacted Bret Timmins resulting in the public domain release of the program.  In this archive you will find the disk image containing the program and the advertised 10,000 word data file, plus a geoWrite file of the manual and a PDF of the printed version which Bruce scanned in.