Yokohama Kaidashi Kikou
One of the best pieces in slice-of-life genre. Very calm and contemplative athmosphere of this unique graphic novell by Ashinano Hitoshi pacifys mind and learns us to see beauty in everyday life. To see gorgeousness of a cloud floating in the sky, to feel warm wind touching your face, to notice days passing by... Not even a smalest thing in our life is insignificant.
If you want to know some more about YKK, there's a good review at Animefringe and a wikipedian article.
Yokohama Kaidashi Kikou is not published in english by now, but there is a very good fan scanlation, a scan translation, done at misago.org. The web site is down for a long time now, but you can download their scanlation from Megaupload or from boxtorrents. It's a torrent download, so if you aren't familiar with torrents, just tell me, I'll explain you how to use it. There's also another scanlation by OneManga, you can read it online at their site.