here in Hebrew) that she may say kaddish when ten men are assembled for prayer or learning (the times when a man would be saying kaddish in this situation).
(You can read about this psak - with a short excerpt translated at the Vos Is Neias site.)
Although the practice of women saying kaddish is referred to historically it still is not universally accepted practice. It is interesting that the custom is becoming accepted in many synagogues as well. (Rav Ovadia specifically does not allow the practice in synagogue - but only in a private home.) Rabbi Hershel Schachter of Yeshiva University in a very encompassing lecture available at the YU Torah Online site "Halacha and Modern Family" states that the merit of saying kaddish in memory of a parent is specific to the children of that parent.Rabbi Schachter tells us that the deceased is judged not only by his own deeds but by the legacy s/he leaves behind in the world. The deceased direct descendants therefore show their devotion to mitzvot by saying kaddish and doing other mitzvot in their memory over the period of mourning. The yahrtzeit is considered a date when not only the judgement of soul of the deceased is reviewed in heaven but also the actions of their children and grandchildren are scrutinized. He brings up the practice of asking someone who is not a relative say kaddish in the case say where there are no sons to do so. He says that some women are not comfortable saying kaddish in shul so they might ask someone else to say kaddish for their parent. But the direction that he is taking is definitely that in terms of the effect on the parents soul in heaven it is well served if she herself says the kaddish. In the shul where I go, women do say kaddish (along with the men) and it is satisfying to see that this is becoming more widely accepted.
In poking around on Rav Ovadia's halacha site I found this psak in English this time relating to women saying the HaGomel blessing upon being saved from some catastrophe or recovering from an illness. He maintains that the women can and should recite this blessing in the synagogue with ten men answering amen.