I agree, this might be kind of nice.

I installed a couple of Wordpress mood plugins and even logged into my LiveJournal account for the first time in about 3 years so I could see what a mood plugin would look like. It seems to me that all any of them do is insert some text above or below the main post text that says:

Current mood: happy
Current music: Rusted Root

or something like that. Wouldn't it be just as easy to just type that in to your post? LiveJournal adds a smiley, but b2evolution already has smilies, so you could just add one yourself. I may be missing something. Are you wanting some special formatting that would take too long to type in each time? If so, then I could make a renderer plugin that does something like that.

If you use www.last.fm then you can generate an rss feed of recently played tracks from an audioscrobbler plugin installed into your media player.

It would be fairly easy to then add this as a sidebar item using magpie rss.