hetfic is running its annual ficathon, and sign-ups end on April 30th.
eurekathon is running round 2.0 of the Eureka gen ficathon. Sign-ups also end on April 30th. (Erm. Given that I'm running this ficathon, trust me, female character prompts are welcome!)
Also, for the next 48 hours, medie is taking prompts for the first annual "because we are awesome" female character-centric drabblethon.