Is there a registry of Book of Mormon Geography Theories?

The official answer is "No"

There is no "registry" of Book of Mormon geography theories because the word implies some sort of authoritative compilation. To my knowledge, the Church keeps no such list (or, perhaps more precisely, I have never seen evidence that the Church keeps a public list).

The unofficial answer is "Yes"

A non-profit organization originally called "The Foundation for Apologetic Information & Research" that is known today as FairMormon is an unofficial archive of many of the theories (of not all...) that have been proposed over the decades. From their website we read:

FairMormon was formed in late 1997 by a group of LDS defenders of the faith who frequented the America Online Mormonism message boards. In defending the Church against detractors there, this small group realized that they had no way of sharing their information with each other, much less the rest of the Church. As a result of this, FairMormon was born. Incorporated as a non-profit organization in the state of New York on December 19, 1997, as The Foundation for Apologetic Information and Research, Inc., or FAIR, the fledgling organization put up its first Web site in March 1998. In 2013, the group became known as FairMormon.

FairMormon is staffed completely by volunteers who are students of the scriptures, ancient languages, early Christian history, early LDS history, and LDS doctrine and apologetics. Most all of the staff here at FairMormon have been involved in online services and Internet-based LDS apologetics for many years. Many of our members are authors of currently-available apologetic publications.

FairMormon's site contains a list of 70+ theories that looks fairly comprehensive. However, it's very disappointing that the links on the page go nowhere other than a nearly trivial summary of the model (what was the "narrow neck of land," where was "Cumorah," etc.). This would be an excellent starting point, but it looks like you'd be on your own tracking down the listed theories for their full detail. (I could have wished they would have at least listed, where available, the book and/or article that presents the theory, so you wouldn't be forced to do so much research.)

Please note two other pages of interest:

• The geography opening page, which has a great deal more information than just the western-world geographies. And...

• FairMormon's statement concerning an official Church position concerning BoM geography. (Short version: it doesn't have one.)

In keeping with Stack Exchange's preference to not be a link-only answer (and, if you think about it, everything before this was a "link only answer"), here's the list available on that linked FairMormon page as of the date of this post.

• Model name: Allen 1989
• Model name: Bagley 1927
• Model name: Birrell 1948
• Model name: Christensen 1969
• Model name: Clark 1989
• Model name: Com.-Maes 1880
• Model name: Curtis 1988
• Model name: DeLong 1977
• Model name: Dixon 1958
• Model name: Driggs 1925
• Model name: Ellsworth 1980
• Model name: Ferguson 1947
• Model name: Ferguson-Hunter 1950
• Model name: General 1830s
• Model name: Goble-May 2002
• Model name: Goble 2004
• Model name: Gunsolley 1922
• Model name: Hammond 1959
• Model name: Hanson 1951
• Model name: Hauck 1988
• Model name: Hills 1917
• Model name: Hobby-Smith 1988
• Model name: Holley 1983
• Model name: Jakeman 1940s
• Model name: Kocherhans 1986
• Model name: Lauritzen n.d.
• Model name: Laytons 1940?
• Model name: Le Poidevin 1977
• Model name: Lesh 1980
• Model name: Loving 1976
• Model name: Lowe 1960a
• Model name: Lowe 1960b
• Model name: Lowe 1970s
• Model name: Ludlow 1976
• Model name: Ludlow 1964
• Model name: Meldrum 2003
• Model name: Nielson 1987
• Model name: Norman 1966
• Model name: Olive 2001
• Model name: Palmer 1981
• Model name: Pate 2002
• Model name: Pierce 1954
• Model name: Plain Facts 1887
• Model name: Porritt 1985
• Model name: Poulsen 2004
• Model name: Pratt 1866
• Model name: Priddis 1975
• Model name: Proctor 1988
• Model name: Qulter 1988
• Model name: Reynolds 1880
• Model name: Ricks 1904
• Model name: RLDS/Wes 1900?
• Model name: Roberts 1888
• Model name: Robison 1977
• Model name: Rosenvall and Rosenvall 2009
• Model name: Sahlin 1987
• Model name: Simmons 1948
• Model name: Sjodhal 1927
• Model name: Sorenson 1955
• Model name: Steede 1975
• Model name: Stout 1950
• Model name: Sudweeks 2013
• Model name: Times and Seasons 1842
• Model name: TRUE-BOMG 2004
• Model name: Tyler n.d.
• Model name: Vincent 1960?
• Model name: Warren 1960
• Model name: Warren 1961
• Model name: Warren 1987
• Model name: Washburn 1939
• Model name: Wilde 1947
• Model name: Wunderli 2002
• Model name: Young pre-1920?