I've written about pro-ana websites before.
As dangerous as those are I believe the thing that was MOST detrimental was my discovery of pro-ana message boards.
On a pro-ana website you are somewhat limited in the "support" you glean from the person that created the site. They rarely communicate directly with you. It's a one sided sort of relationship. You click and read and that's about it.
A message board is much more personal.
On a message board you get to know people. You get feedback for your posts. This isn't always healthy. Yes, if you decide that you want to go into recovery MOST people will cheer you on with comments like "you're so strong" and "I wish I could do that!"
But what if your post isn't about getting healthy? What if it's just the opposite?
Well you receive support for that too. Not in a "cheer you on" sort of fashion but in a "hey, it's okay" sort of way.
I remember reading where a girl admitted to purging in a car full of people. Her trick was that she feigned carsickness and put her head into a big black trashbag. A lot of the comments were along the lines of "I wish I were brave enough to do something like that." I'm not saying she should have been condemned...but she certainly didn't need applause.
The boards I belonged to didn't allow "tips" for legal reasons. However, I can tell you from experience that you can glean tips from reading someone else's experiences. Like with the above story, she didn't give a "tip" for purging in public but you can bet a dozen people read that and thought "That is so creative!" I did.
I will say I met a few good friends on that board. A couple I'm in touch with to this day. However, some of the meanest people I've EVER encountered were there. The anonymity of the internet combined with emotional issues makes for a bad time.
I was pretty tempted to head over to the board (where I still have access) and screenshot a few things to make my point. In the end, I couldn't do it for many reasons...
1) The board owner really doesn't like me. I'm sure she'd love to tear me apart over that.
2) Somewhere inside me I still have an emotional attachment to it. For a long time it was my safe place. When I felt like no one in the world understood me I could go there and know that at least one person did. If only it hadn't also been the place that fueled my disordered thinking at times...