Try albasani.net or eternal-september.org . I still haven't got registered for albasani.net. There is quite a lot of spam on eternal-september.org but it works well as a service. Maybe you can try aioe.org. Here is a list of news servers for #Usenet: http://www.dmoz.org/Computers/Usenet/PublicNewsServers/.

You might want to check #DOVE-Net. DOVE-Net has a central node that the sub-nodes connect to to push and pull messages. I am registered on #EWBBS (bbs.ewbbs.net) and they run an NNTP gateway to their #DOVE-Net hosted messages.

For a client. Try #Pan or #Thunderbird (works better for me).