I like Abort73 - it's no secret. If you're on Facebook, I've probably tried to recruit you.
Founder and director Michael Spielman has put together a compelling booklet (that sounds like a contradiction: "compelling booklet") called A Biblical Mandate to Do Something About Abortion. The title kind of says it all.
You can buy it on their website or, true to Abort73-loves-freedom-of-information form, you can download a PDF of the entire thing ("entire," it's 32 half-pages) here. I read it. It's pretty good. Some excerpts:
"We know it's happening; we know it's bad; but we seem content to remain as uninformed as possible, as if a general ignorance on the subject will somehow clear us of moral responsibility."
"The Old Testament accounts of child sacrifice give us as close a parallell to abortion as anything we'll find in Scripture. Though the nature of the idols has changed, the sacrifice is virutally the same. The false gods of today are not Molech or Baal, but wealth, freedom, and autonomy."
"With all of the lobbying, all of the rallying, and all of the petitioning, why do legislative efforts continue to fail? The fact is, most people just don't care about abortion. ... They don't care because they don't know. ... It [abortion] has never stood the test of full-disclosure, nor could it."
So if you want to know more, check out their website. I've never seen a website with so much information on it - but at the same time it's very organized and not one of those websites you get lost in.