There's a list going around 2channel of which seiyuus are getting multiple roles in new anime this season. I'll just accept that the list is accurate and make some comments. It doesn't include continuing anime, just anime that are starting this season. (mouseover images for captions)
6 shows -- Kamiya Hiroshi
The king of the moment.
5 shows -- Chou, Yoshino Hiroyuki, Namikawa Daisuke; Hanazawa Kana
More female seiyuus in the business means fewer roles each. Kana-chan is the only woman to reach these heights, and then only with Wednesday's announcement of her role in the Black Rock Shooter OVA.
4 roles -- Fujiwara Keiji, Fukuyama Jun; Taketatsu Ayana, Sawashiro Miyuki
The big surprise here is Taketatsu Ayana, who burst to prominence as Azu-nyan in K-On, and has become a producers' darling, with roles in Jewelpet 2, KissxSis, K-On 2, and Mayoi Neko Overrun -- as well as her continuing role in Yumeiro Patissiere.
3 roles -- (men) Yasumoto Hiroki, Okamoto Nobuhiko, Takahashi Hiroki, Ono Daisuke, Hida Nobuo, Kimura Ryouhei, Sakurai Takahiro
(women) Asumi Kana, Itou Shizuka, Sakamoto maaya, Shishido Rumi, Kobayashi Yuu, Ueda Kana, Hikasa Youko, Toyosaki Aki, Horie Yui
Here we see the return of two excellent veteran stars to multiple roles: Sakamoto Maaya and Shishido Rumi. And we see the continuing effect of K-On on the careers of its stars (two of whom are Hikasa Youko and Toyosaki Aki), just as Suzumiya Haruhi energuized the careers of its stars. It's also interesting to see how much Eden of the East did for Kimua Ryouhei's career.
2 roles -- (men) Itou Kentarou, Takahashi Jun, Kuroda Takaya, Miki Shinichirou, Yamaguchi Kappei, Koyasu Takehito, Koyama Rikiya, Morikubou Shoutarou, Morikawa Toshiyuki, Morita Masakazu, Suwabe Junichirou, Mizushima Takahiro, Sugiyama Noriaki, Ishida Akira, Ishii Kouji, Ishizuka Unshou, Asanuma Shintarou, Kusao Takeshi, Yonaga Tsubasa, Ohkawa Tohru, Okiayu Ryoutarou, Nagasako Takashi, Hino Satoshi, Takeuchi Ken, Houshi Souichirou, Yasumura Makoto, Usa Kouji.
(women) Suzuki Chihiro, Nagata Yoriko, Kitamura Eri, Kuwashima Houko, Hirohashi Ryou, Kaida Yuuki, Kaida Yuuko, Noto Mamiko, Satou Satomi, Saitou Chiwa, Asano Masami, Tamura Yukari, Tanaka Rie, Paku Romi, Yuuki Aoi, Hayashibara Megumi.
Seiyuus do get other work: dubbing (Sakamoto Maaya and Kaida Yuuko both do a lot), voiceovers, etc., But it seems to me that multiple roles is about the only way to make a living as an actual seiyuu. The list is full of the usual reliable voices: Koyasu Takehito, Koyama Rikiya, Ueda Kana, Horie Yui, Paku Romi, Tanaka Rie, et al. With some younger voices finding their way in: Kitamura Eri, Yuuki Aoi, Satou Satomi. And an older star getting multiple roles again: Hayashibara Megumi.
Of course, many of these people are also in shows continuing from the winter: Yuuki Aoi is in Yumeiro Patissiere and Kiruminzuu, as well as the new shows Yutori-chan and Ichiban Ushiro no Daimaou.
Some big names don't show up at all in the new shows, not even with one role: Kawasumi Ayako and Kugimiya Rie, for two examples, are only in single episodes of continuing OVAs (ToLoveRu and Utawarerumono, respectively). But that could turn around completely next season.
And one of my favorites, Hayami Saori, doesn't have a new role until the summer. She may be concentrating on getting her greater talent of singing ready for a career there. Or else she may be concentrating on school, which is apparently not her strong suit, as she hopes to enter college. Or her so-far limited range may not endear her to producers.