I was thinking, for each month, week, whatever, generate a chart, showing posts per day, comments per day, perhaps a comments to posts ratio, maybe (if it's stored) friends added / removed per day, etc.
I thought of this because I was wondering earlier how my posting habits had changed; so I took 10 minutes and used the calendar to make a list of every day I had posted and how many, put them into excel, and graphed it. Then, to further satisfy my curiosity, I did the same thing with comments, and as a third column, (comments/posts)*10. (I don't get enough comments each day to have my ratio come anywhere near my actual number of posts ;) )
What point? None, really - but it was interesting to see. It was also interesting to see, when I had gotten quite ill for a few days, when Christmas came, when other events like that happened, how it affected my posts. It's all trivia and rather pointless, but interesting trivia, if you ask me.
Now, I know it'd take someone familiar with GD, or perhaps something like MRTG's graphing component (RRDtool or something, I forget, and which would probably be overkill, but...), to write a script to graph this sort of thing and generate it on the fly. I'm not overly familiar with either but reviewing them briefly it seems simple enough, albeit a bit of a cpu-hog. Maybe if they were generated periodically rather than on the fly? I dunno. Just a thought, anyway, figured it might be a fun little feature.