Well, for Flickr, I'd say that the photographs that get noticed are often by people that are group active rather than necessarily all that good. Not to say that there aren't great shots that don't get noticed otherwise, but if you look at "interesting" you'll find some that aren't really all that interesting at all, just that they got a lot of group hits.
In terms of getting critique, the offline option is camera clubs. Some are better than others, but being in one or, if needed, forming one, is a good way to get good advice. For example, just today, I was testing out the focus tracking and burst capabilities of my new Pentax K5 with a friend in our local camera group (both of us have the K5). I posted a swan in flight, but I over-sharpened it and he called to let me know. I realized it shortly after posting, but having a good shooter call me to minutes after posting was a good thing and I appreciated it. He was even spot on for the reason, I pushed the clarity slider in ACR too much.
In any case, in my opinion, I like the face-to-face or phone call better for this sort of thing. Critique is hard in an online context, it can come across very harsh. I do a lot of code reviews as a software architect and, when I reopen tasks with review comments as a result, I almost always go over to the developer for a chat after because I want them to know and feel that it wasn't personal and I want to explain certain things verbally that just are too hard to make clear in an email. I see that as a way to make them better coders and I think it works, at least results are bearing me out.