First, of course, is the fact that linguistics is a small field (I'm near certain that Language Log had a post in the last few months regarding the small size of linguistics compared to other fields, but I've failed miserably to find it). There simply aren't enough of us to cause any controversies, except when someone wants us to prove that "X" is not really a word and we refuse (see Zwicky's relevant post here).
Second, there are many easily recognizable female linguists who have been highly influential. Off the top of my head I can easily think of Barbara Partee, Adele Goldberg, Joan Bresnan, Joan Bybee, Eve Sweetser, and Eve Clark , amongst a great many others (hehe, that list TOTALLY marks me as a Buffalo functionalist).
At least as interestingly, the highly technical sub-field of computational linguistics/NLP is brimming with examples of influential female scholars, such as Ann Copestake, Paola Merlo, Bonnie Dorr, Tanya Reinhart, and Jan Weibe to name a just a small few.
The only sub-field of linguistics that seems to be male dominated is syntactic theory invention. I can think of many males who are strongly associated with the invention of a theory of syntax/grammar (though, in all honesty, no one person truly invents a theory alone), but only Goldberg & Michaelis's construction grammar comes to mind as a theory of grammar designed by female linguists (I happily solicit examples of my ignorance). Whereas, a list of male-invented grammatical frameworks/theories is easy to compile:
- N. Chomsky --> Minimalism, GB, Transformational Grammer
- G. Gazdar --> Generalized Phrase Structure Grammar
- Pollard & Sag--> HPSG
- Van Valin & LaPolla --> Role and Reference Grammar
- D. Perlmutter --> Relational Grammar
- C. Fillmore --> Case Grammar
- R. Langacker --> Cognitive Grammar
UPDATE (Nov 28, 2009): There are many excellent additions in the comments.