ReadWritePoem has a mission that feels very similar to Poets Online -
Read Write Poem is an online gathering place for those who love poetry — and for those who suspect that, with a little nurturing, they could grow to love poetry. Whether you are new to writing poetry or have been writing for years, you are welcome here. If you don’t write poetry but love to read and discuss it, this is also the place for you. (And who knows? After participating for a few months, you might realize you want to try your hand at writing a poem or two after all.)- but they certainly have more staff than Poets Online since it's hard to get smaller than one.
I came across the site via a guest prompt by Dorianne Laux that is a good place to start.