There have been numerous historical and more recent memory systems, most of which follow a few basic patterns. This page gives short descriptions of memory systems for comparison. Also see the discussion of the continued relevance of memory systems at MemorySystems21stCentury.
Many of these had a mystical component and are primarily thought of as occult or mystical systems instead of memory systems. They tend to be based on a LinkSystem or PegSystem (or perhaps two or more such systems cross-referenced to create a MemoryPalace.) Examples: astrology, kabballah.
Ancient and classical memory techniques distinct from mysticism usually involved rhymes or alliteration, word play, acrostics, or other tricks to make a phrase more memorable. Examples: poetry and folklore in rhyme, Celtic Ogham lists.
A few systems used visualization and linking, especially to places, which lead to MemoryPalace techniques explicitly defined as memory techniques. Examples: the Roman Room system.
Ramon Llull's system relies more on systemization to relate new concepts to already-learned concepts, which makes it related to a PegSystem or LinkSystem, but without the visualization and action we would normally associate with modern techniques. Giordano Bruno's system modified the Llull system by creating pegs/loci using astrological symbols and specifying that each loci should contain an actor performing some action.
Modern systems are mostly based on the visualization and action principles recommended by Giordano Bruno combined with either a set of real-world loci as pegs (an alteration of the Roman room system) or a systematic PegSystem developed using NumberSystems or AlphabetSystems.
The DominicSystem: detailed in "How to Develop a Perfect Memory" by Dominic O'Brien.
FurstSystem: detailed in "You Can Remember" by Dr. Bruno Furst. Based on two 100-image PegSystems and the MajorSystem.
MegaMemory: created by Kevin Trudeau. Based on several NumberSystems and ad-hoc RomanRoom lists used as peg lists, but also includes a BodyList. (Some of Trudeau's other books, such as Natural Cures, have been discredited, but MegaMemory is a fairly vanilla memory system.)
Can other people more familiar with other systems add them here? --- JohnLaviolette