I stumbled across it a few months ago on the Anime News Network - it was one of the top ten best rated shows and I hadn't ever heard of it, so it peaked my interest. It just finished airing and the english subs are quite a bit behind (21 available at the moment), which sucks, but from what I've seen the show is excellent and has become one of my favourites. It's a great show to unwind to at the end of the day - not a lot of people being sliced up, but strangely enough worthwhile to watch regardless.
From Anime News Network:
They are neither plants nor animals. They differ from other forms of life such as the micro-organisms and the fungi. Instead they resemble the primeval body of life and are generally known as "Mushi". Their existence and appearance are unknown to many and only a limited number of humans are aware of them. Ginko is a "Mushi-shi" who travels around to investigate and find out more about the "Mushi". In the process, he also lends a helping hand to people who face problems with supernatural occurances which may be related to the "Mushi".
Images:
Links to downloads:
http://www.c1anime.net/projects.php?project=Mushishi
