I usually use Merlin's portal, I'm a VIP, it's got the best search engine, most other nzb sites suck. Why people are slagging off Merlin I don't know, problems ocurred after they changed providers, since then the database has been knackered or hacked or whatever? I hope it comes back soon, I miss it.... the site below is about the best of the rest.
http://nzbmatrix.com/index.php
DAVEdeFEET