Cyan Banister because of her accomplishments in tech and art, 'cause Zivity is cool and because her personal story was compelling to me. Libertarian philosophy, thoughtful writing, skills of the super-techy kind, AND friends w/Penn Jillette. (Jealous much?) Check her out at twitter.
Karen Stollznow - skeptic, scientist, writer. Have to admit - I mostly picked her because she is a self-described cunning linguist. But in addition to her wit, she is Director of Bay Area Skeptics She tweets @karenstollznow, too.
Jean Kirkpatrick was a sociologist and the founder of Women for Sobriety. I only know Jean because of WFS, her related writings and autobiography, and meeting some of her many friends. She was an alcoholic who came up with WFS while getting sober without "that other program".
Also in celebration of Ada's day, check out the launch of shethought.com - I contributed an essay (first time I've submitted writing to somebody else, leaves me excited and a little nervous!). Not up yet, will tweet when it is.