Critters, aka www.Critique.org, is a genre writing/critiquing service run by the current Science Fiction and Fantasy Writers of America (SFWA) vice-president, Dr. Andrew Burt. It's a free system, designed to generate meaningful feedback to SF, Fantasy and Horror authors.

To participate, one signs up on the website. After an account is created, you are expected to post a critique of a story or novel, three per month. Professional writers, such as SFWA and Horror Writers of America (HWA) full members, are asked to post one per month. In return, you can submit your stories for critique.

I've used this service several times, and with one exception, the feedback has been exemplary. Sometimes a critical eye can spot glaring holes in a plotline, or a series of grammatical errors, better than the author can.

Did I mention this service is free? You get a lot of quality feedback in return for your quality feedback.

They do have a couple of extra benefits, such as a 'woo-hoo' page, where you can post your sales and achievements.

As a member of the Horror Writers Association, I've found the service to be very useful when it's time to polish your short stories. I have two pro-pay stories that would've been rejected if I had submitted them as-is. It's not as fun and crazy as E2, but the benefits can get you published.