I've heard that there are situations in which one can count the ladies towards a Minyan. Is that true? Which situations?
I think it's the case where a non-Jew is trying to force a Jew to violate any mitzvah (or even any established Jewish custom) out of opposition to Judaism (rather than for some personal benefit). If ten Jews - and if I recall correctly, women are included - know about the situation, then as part of the mitzvah of kiddush Hashem, the Jew has to allow himself or herself to be killed rather than violate the mitzvah.
(Shulchan Aruch, Yoreh De'ah 157:1. Pischei Teshuvah there :7 mentions the question whether women count towards the ten, and references his comments to Yoreh De'ah 2:6, but I haven't yet found it there.)
One should try to read the Megillah for at least 10. There is a disagreement about whether women may be counted towards this total.