Might I suggest another one? OWWW is Other Worlds Writers Workshop and I've been a member there for years. Excellent feedback from writers that are making it happen (getting published). They have strict rules regarding participation but I'm guessing you've already found that to be true with Critters. It's the strict rules that keep it strong, in my opinion. You can check it out here: http://www.otherworlds.net/
. There's lots of great info there, even if you don't join. You have to do 6 crits before you sub and then they expect a ratio of 2 crits/1 sub per month. When you join, the actual business end is a yahoo group. Very easy to use. Great people. They conduct seperate writers classes for a modest fee as well.
Sending your stuff to FTL (for the love, not faster than light) markets gives you exposure. I have posted stories on my site but most of my short fiction I'm sending out to paying and non-paying markets both on and off the web.
Contests sometimes provide valuable feedback with the rejection slips.
Many SF conventions have a writer's workshop. I participated in one at BayCon in San Jose, CA. That con also had a lot of useful panel discussions and talks on elements of writing speculative fiction.
Good luck with Critters and I hope some of my suggestions are of use to you.