I found and (re)read In the Best of Times by Kiera (Willow/Giles - he's not the baby!daddy).
I know there were some other good ones out there. I'm vaguely remembering a Willow/Spike - or was it Willow/Angel? - story where Willow was raped by a human and gets pregnant and the vamp helps her care for the baby. I think it was one of the vamps. Could have been Giles again.
And yes, instead of reading new fic that's been posted, I'm chasing down old stories to re-read.
I think this craving came on after reading Positive Affirmations (River/Mal) by apckrfan. I highly recommend it. I don't generally read Firefly fic, but when she told me about it the premise intrigued me.