The flotsam and jetsam that washes up on the Magazine Reader's beach can make for absorbing, if rather specialized, fare. The little-known publications mentioned here, a random sample of recent arrivals, suggest the exotic varieties of editorial concern and the pervasive influence of desktop computer publishing.

Journal of Defense & Diplomacy, a monthly publication, calls itself "The Magazine of World Leaders," though presumably mere citizens may subscribe. The journal is evidently aimed at people interested in questions of geopolitical strategy, with special attention to guns and bombs. Every issue contains a map describing the status of global crisis points, a list of the latest military contracts (who's building what weapon for whom) and selected country profiles with their key defense facts and offerings of opinion -- generally conservative. For a year's subscription, send $42 to Journal of Defense and Diplomacy, 6819 Elm St., McLean, Va. 22101.

American Brewer results from the merger of Home Fermenter's Digest and Amateur Brewer, you'll be interested to know. It's subtitled "The Micro-Brewer/Brew-Pub Magazine" and covers, with zest and sufficient irony, the high standards and sometimes fractious disputes in the growing world of beer purists. The summer issue of this quarterly magazine takes up the ways and means of brewing wheat beer. A year's subscription, typos and all, costs $13.50; write American Brewer, Box 713, Hayward, Calif. 94543.

Antipodes has only published one issue and plans to publish only twice a year. It describes itself as "A North American Journal of Australian Literature," so if you'd like to know how the learned and the expert view Patrick White, Colleen McCullough, Shirley Hazzard, A.D. Hope, Thomas Keneally and Robert Hughes, among other Australian writers, send your check for $12 (issues are published in March and November) to Antipodes, 190 Sixth Ave., Brooklyn, N.Y. 11217.

The Other Side, established in 1965, "is an independent, nonprofit, ecumenical magazine for Christians who ... seek to be in solidarity with struggling sisters and brothers in some of the poorest, most oppressed parts of the world." For example, a recent issue (the magazine's publishing schedule is too complicated to describe) contains a lengthy report on the FBI's "secret war" against the American Indian Movement. For a year's subscription ($19.75), write to The Other Side, 300 W. Apsley St., Philadelphia, Pa. 19144.

International Wildlife is a bimonthly of striking good looks, published by the National Wildlife Federation. The July-August issue pays tribute to the field illustrations of the late Terry Shortt; explains how a few brave swimmers in the Philippines collect venomous sea serpents with their bare hands; and examines one chemist's theory that termites in Kenya emit enough methane gas to influence the world's climate. Write the National Wildlife Federation, 1412 16th St. NW, Washington, D.C. 20036: A $15 membership buys you a year's worth of International Wildlife or its companion magazine, National Wildlife; $20 buys you both.

SOMA is not about sleep; it's named for the South of Market Street artistic community in San Francisco, and it's quite a lively quarterly. The summer issue, along with regular fiction, poetry, fashion, design and arts coverage and gallery listings, has a story about art directors of Bay area-based magazines, including Veronique Vienne of Parenting and Rudy Vanderlans of Emigre: The Magazine That Ignores Boundaries, an intriguing name in itself. A four-issue subscription costs $10; write SOMA, 283 Ninth St., San Francisco, Calif. 94103.

Ame'ricas is published by the Organization of American States in two editions, English and Spanish. If you enjoy reading about your hemisphere but are sick and tired of hearing about the contras and the Sandinistas, the Third World debt crisis, bloody dictatorships and the destruction of tropical rain forests, this is the magazine for you. The July-August issue has stories on Bolivian hats, the Pan American games, a Barbados street celebration called Crop Over, and iguanas in Panama. Six bimonthly issues are available at $9.90; write Ame'ricas, P.O. Box 973, Farmingdale, N.Y. 11737, and specify English or Spanish.

Divorce doesn't exist yet, but plans are under way to launch "The Magazine for People Starting Over" in October. Stories will explore the legal, financial and psychological dimensions of divorce, and something called its "lighter side," according to a news release. Watch for this bimonthly magazine on your newsstand; the publisher doesn't expect anyone will need the magazine long enough to subscribe to it.