This #nostr relay project from a few months ago has gone with little notice, but I think it's still a dope relay implementation. It's the reverse version of Blastr. You can't publish notes to it. But it REQs from as many listed online relays as possible using the nostr.watch API. 

You can use it with wss://unostr.site

Or build your own using a Cloudflare worker: 

https://github.com/Spl0itable/unostr