I belong and infrequently contribute to the Live Journal community, toot_toots. The posting rules are simple, 4 or 5 lines constrained so that the first character of each line combine to spell the word 'toot' or 'toots.' I enjoy creating within the constraint. The fun in the process is similar to that of writing poetic rhymes. With a bit of extra effort one can combine the two. I've made a recent post. It's a good way to use idle brain-cell cycles; you should try it!