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Yes, others write microfiction. (I write 100-word stories.) There are several journals (online and print) that publish it. You don't ask about publishing, but you could start with @Tiny_Text and 100WordStory. Cupboard publishes really interesting chapbooks of tiny fiction. I don't know of any online communities, but they might be out there.
It is worthwhile also searching for flash-fiction; although this can be up to 1000 words it will often be shorter. Also 'drabble' is another name for works of circa 100 word lengths. I myself write humorous flash-fiction, but don't really belong to any communities.
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