This is the text of my correspondence to Nature on gender balance at conferences (Nature 493, 305; 2013: published version here: http://dx.doi.org/10.1038/493305c)
Sexism: conferences should seek a balance
Conference committees and symposia chairs should follow Nature’s lead and be more open and proactive about gender balance (Nature 491, 495; 2012).
Publishing an online declaration of gender-balance policy would help. Data from each of the past, say, three meetings could also be posted online to indicate the percentage of women who were registrants; invited plenary and keynote speakers; session speakers; programme committee members and session chairs. If there is a significant gap between the percentage of women attending the conference and the overall percentage of women speakers or committee members, then a policy overhaul may be called for.