Thanks for the tip Vincent. Looks like there is no way to do a random sort. Your right, any input except "results" prints in alphabetical order. Random order would be a nice option, making a better looking cloud.
Just out of curiosity, I googled word cloud images & couldn't find any that were sorted alphabetically.
BTW, I would guess that some consideration should be made for how a "random" sort meshes with the limit parameter. Do you randomize before or after taking the limiting function? If you do it before you will get a different set of tags each time the cloud is displayed.
Looking at the printAllTagsAs function it seems only the sortorder "results" is checked. In that case the resutls is sorted by arsort. "abc" is not checked or sorted at all. All tags are fetched by getAllTagsCount(). So either that has been forgotten or got lost. But in any case that must be that way for years...
Interestingly the tags_extras plugin which was modeled after this does not even have a sort parameter.
in getAllTagsCount, you will find this code :
$sql = "SELECT DISTINCT tags.name, tags.id, (SELECT COUNT(*) FROM ".prefix('obj_to_tag')." as object WHERE object.tagid = tags.id) AS count FROM ".prefix('tags')." as tags ORDER BY 'name'" ;
so, in printAllTagsAs, in all case but $sort="results", tags are by alphabetical order.