Hayami Saori is my favorite seiyuu-singer. If you still don't get my enthusiasm, give a listen to these two collections of her songs.
Really, her voice almost brings tears to my eyes, as a poster on 2channel wrote. She just has the most "beautiful" voice I know. So if you like sweet and skilful singing, give it a try.
The links are to pages that take the sound from Nicovideo pages and give non-subscribers a streaming player and the chance to download an mp3. The streaming player is under the main box on the page. The mp3 download is the right-hand tab under the box under that. Click the image above the player to go to the Nicovideo page. I've added an illustration at the bottom of this post, under the fold, that shows you where to click on the Japanese-language page.
Hayamin will be in five series this fall, starring in two, and with important secondary roles in two others. She also stars in one of the two OVAs she is in. She will produce songs for all or nearly all of these shows, so it should be an enjoyable fall. Her CDs are available from CD Japan.
Her thread on 2channel continues to waste its spirit talking about how "ugly" her face is, or defending her against those claims. As far as I'm concerned, she is one of those people who doesn't look so good in still photographs, but is very attractive in videos, because of the way her spirit shines through, and because of the elegance and mobility of her expression.