I used to be a member of a hydrolist email group. It went off line
some time back - I checked with them - "Yes, OL, hope to have it back
one of these days..." That was some time back - have heard nothing.
So....

http://www.blackforest-co.com/bfforum/viewforum.php?f=7 it's free,
some rules about promotion (spec of non-hydro items).

also
http://www.blackforest-co.com/users/hydrolinks/