I heard him already in 90's but started to pay attention to his voice much later. Since I 'discovered' him, I was pretty sensitive to his performing although, I admit, I don't recognize him every time. This is a feature that I truly admire in a seiyuu. For my part, I love when he speaks in a serious manner, his voice becoming quite deep and somewhat penetrating. In that particular pitch he is immediately recognizable.
Nozomu Sasaki was born 1967, Jan 25, and his hometown is Hiroshima. I believe he was pretty popular back in 90's, maybe even 80's, since he played one of the main characters in cult anime "Akira". I never saw the production, but judging from Sasaki's other roles, he's pretty fond of young and, more or less, mysterious men.
Clef from "Magic Knight Rayearth" is probably the first role of Sasaki that I've ever heard. He portrays a powerful magician here... as he does in "Cardcaptor Sakura" (also by CLAMP) as Eriol Hiiragizawa.
Sasaki also managed to play two roles in "Rurouni Kenshin" anime: as Gentatsu Takatsuki, a young samurai who wished for peace, in the motion picture, and as Enishi Yukishiro, not so peace-loving man, in both OVA series.
Those three guys only continue Sasaki's career in portraying young men. Yuusuke Urameshi is a delinquent and a main character in "Yuu Yuu Hakusho", pretty energetic and powerful guy. Julian Mintz from "Legend of the Galactic Heroes" is a follower and a worthy successor of the genius strategist Yang Wenli. Mello from "Death Note" is one of the successor of the genius L, fighting with the psychopath Light.
In the end, probably my favourite roles of Sasaki. Gekkou Hayate from "Naruto", despite his rather short appearance, became one of my most beloved characters in said story. I totally love his calm and somewhat apathetic manner. As for Daikenja (Great Sage), he is a powerful yet gentle mage (yet again), and I really love mages ^^ Sasaki is perfect for such roles indeed.
I may have been overly optimistic making that statement about his career continuing well. To tell the truth, I haven't heard him in anything new. I hope it will change, though, because he has a very unique voice and is capable of playing different and interesting characters.