Again via Invisible College, a link to an interesting article referencing Gematria and combinatorial mathematical systems in general. It is part of The Ineffable Ten Dimensions — the whole site looks like it's well worth reading.
There are three specific types of combinatorial systems. In mathematics, these three types are called permutation, combination, and variation. Each begins with a limited number of items, a set of things. In permutations, the positions of these things are shuffled within the whole set, as in an anagram. For combinations, one can take out any number of elements from the set and put them together in a smaller group. Variations are permutations with repetitions allowed; in variations, one can permute to infinity. certain questions, themes, and comparisons arose. Why are permutations of abstract symbols so often linked to creation, whether divine or artistic? What is it about permuting letters or numbers that leads to mystical experience? Is this experience born out of the creative transformation that occurs or out of the meditative activity? What role can the computer play as a stand-in for this process? What is the qualitative difference between permutational systems that are intentionally driven, and those systems that are manipulated with chance operations?