I regularly check the MyBlogLog widget on a new blog I discover to see if I recognize the faces of other recent readers, as a way to get a feel for the site's community. BlogJuice takes that practice and amplifies its usefulness by orders of magnitude.
MyBlogLog lets users list their accounts on a variety of different services elsewhere and BlogJuice displays readers' job titles via LinkedIn, recent bookmarks on Del.icio.us, StumbleUpon and Digg, recent photos on Flickr, music on Last.fm and videos on YouTube. Clicking on a person's own blog in the display will show you the reader community for the blog they write. Wow.
I'm sure this is only the beginning of what can be done with MyBlogLog and I'm very excited to see what comes next. As I said when the MyBlogLog API launched, for all the good discussion around Data Portability, MyBlogLog is making things happen quickly. It's being done through proprietary technology, under the umbrella of one particular vendor, but damn is it hot.
It's not often that a tool comes along that I can imagine myself using every day. If BlogJuice holds up over time and traffic, this handy little service will join that list for me.