I enjoyed Yuruyuri, but didn't really notice Ookubo Rumi's voice as Chinatsu. It wasn't until Tsumiki in the current show Acchi Kocchi that I have realized Rumi really is a good seiyuu. She is making a moe character even more moe. And she does a quite different character well as Oda Nobunaga in the underappreciated Sengoku Collection. She has a bit of range and understands her roles.
She and four other young seiyuu -- Uesaka Sumire, Komatsu Mikako, Takamori Natsumi, Mikami Shiori -- do a radio show called A+G Next Generation Lady Go!! Each seiyuu hosts a different night of the week. Video of the broadcast is streamed. I caught one of Rumi's nights on NicoNico and was impressed by her fantasy, liveliness, and apparent self-aware irony. She seems like a dangerous character, lol. And oh, yeah: she's sexy as anything.