Would be nice if admins and moderators could see number of subscribers (for e-mail updates) at each item (e.g. blog, forum post etc.) that could accept such (think you don't currently have subscribe-to-blog feature, but hope you'll add such in the future and have some common model for subscribing to updateable items). 

Shouldn't show that info to others I guess to avoid spammers misusing it (to post spam to most subscribed-to posts at forums)