Besides writing small object systems in Univac Lisp, Le-Lisp, Common Lisp and Scheme (as every Lisper does), I wrote a first paper with Pierre Cointe on them: LFP88. We presented an open-ended model where the structure of objects was held in metaclasses.
I extended this paper in JFLA90 where I dealt with other data representations. An interesting output was the design of the Meroon object system for Scheme. The first paper describing it is its reference manual followed by another paper describing its most salient features OOPL:LA93 as well as some other problems that were solved in Meroon V3.
This dispatch technique has been improved in the recent versions of Meroon V3 and is described in a paper to appear in IPL.
There exists a light version of Meroon named Meroonet fully explained in one chapter of my latest book.
These studies helped in the design of the Icslas language that features a distributed object system logically(?) named DMeroon.
See also a paper on generic distributed functions.