Adding functionality to wp_tag_cloud…

I’d like to add the ability to “order by” chronologically. I assume that means adding a time element to the term_taxonomy, such as last_posted or something to that effect.

I’ve added Serieses to my posts, and that’s my main need to the chronological aspect. On my site, a Series is a game or event, and I’ll have four or five Posts related to that Series. I don’t want it tied to the date of the game or the event. I want it tied to the when I make the Post, so any time I Tag something, that Tag would pop up to the top of my list, in this case Series.