What's an efficient, low-cost, secure way to facilitate an online support group?

I’m not quite sure exactly what I’m looking for. I know you can use Yahoo groups, or equivalents in other places, but those seem kind of clunky to me. I’d kind of like a newgroupy feel, or a bloggy feel, but also friendly and encouraging. It’s hard to describe it, probably because I don’t know exactly what is needed.

If you have experience with this, please let me know. Also, if you could talk about the advantages and drawbacks for each solution you can think of, I would be very grateful.