I have and do call myself a feminist. Despite the fact that many people here have stated that its meaning has changed and now includes a bunch of connotations, mostly due to it being used as a shield to cover up for sexism and sexually repressive attitudes and behaviour.
Our choices appear to be either to fight to keep possession of that word to its dictionary definition or abandon it to those who would use it as a cover for their performance of the very antithesis of what the term actually means, or some unrelated activity. So far I'd rather attack those people and correctly identify them as the sexists, repressive or nuts as it applies.
I can understand the argument that the term is has a focus problem, it says female equality, which in logical terms is the same as male equality, or gender equality, but carries with it, the sniff of the Orwellian concept that some are more equal than others.
That it should perhaps be given over and a new term employed by those serious about feminism; humanism being given as one example, gender egalitarianism as another.
However I have a concern about this:
If you say, ah we'll abandon this word to the fringe lunatics and sexists masquerading as egalitarians then will you have to make the same surrender when they eventually want to use your next term for gender egalitarianism as a cover for their sexist and/or oppressive attitudes?
So far I have acted to fight for ownership of the term, I could be convinced that its focus limitation, its misuse, and its lack of integration with other important concepts like freedom, mean gender egalitarianism (for focus solely on equality) or humanism (for focus on a broader range of human centric issues) should be employed instead yet as I stated I can see some problems with such a choice.
Edit: As for activism, it depends what counts. I have advocated publicly (edit 2: I mean in the talking about, rather than legal sense) for various matters of gender equality. Retirement age, working conditions, parental access, other issues tied largely to humanism and children's rights like being against genital mutilation of children although unlike some I don't only focus on one gender.