Ai Nonaka - Serene from Riviera (video game, but hey D=), Fuuko Ibuki from Clannad, Pamela and Emilia from Yggdra Union (video game; PSP version only)
Houko Kuwashima - Maron Kusakabe from Kamikaze Kaitou Jeanne, Tomoyo Sakagami from Clannad
Mai Nakahara - Rena Ryuuguu from Higurashi, Nagisa Furukawa from Clannad, Yggdra from Yggdra Union (video game; PSP version only)
Miyuki Sawashiro - Kazune Kujyou from Kamichama Karin, Milanor from Yggdra Union (PSP version only, and yes this is another video game XD), Ultear and Virgo and Ur from Fairy Tail (<3)
Rie Kugimiya - Ein/Ecthel from Riviera (once again, video game), Happy from Fairy Tail (<3), Karen from Luminous Arc 2 (video game), Palom and Porom from Final Fantasy IV DS (video game), Shannon from Umineko
Tetsuya Kakihara - Simon from Gurren Lagann, Natsu Dragneel from Fairy Tail (<333; points to username)
Aya Hirano - Haruhi Suzumiya (OK, really now, if you do not know what series she's from, well... XD), Lucy Heartfilia from Fairy Tail (<3), Lucia from Luminous Arc (video game)
English
Veronica Taylor - Ash Ketchum's first voice actor from Pokemon, Max Taylor from Dinosaur King, Tamara from Shaman King (using her dub name because, well...yeah)
Sebastian Arcelus - Rex Owen/Ancient from Dinosaur King, Yoh and Zeke (once again dub name) Asakura from Shaman King
Yuri Lowenthal - Haru Glory from Groove Adventure Rave/Rave Master (<3), Ein from Riviera (video game), Lok Lambert from Huntik (yes I actually watched this now shut up >:[), Simon from Gurren Lagann, Cecil Harvey from Dissidia: Final Fantasy and from Final Fantasy IV DS (video games), Ben Tennyson from Ben 10: Alien Force, Heath from Luminous Arc (video game)
All I can think of for now :>