I used to have quite a list of good SFB sites, but a lot of them seem to have died or moved (eg John Kim, Sandy Hemenway, Vega). Time to fess up about what's out there.
And here's mine for a start. aaargh.org
Most relevantly, The Thousand Wandering Tribes of which I am genuinely proud and honestly think is a far superior reworking of the Jindarians. Although I'd be the first to admit that it's not been playtested by any ace-level players, so you may find something a bit bent, especially in the big asteroids. There are even a couple of TCs. I've scarcely mentioned this lot on the ADB BBS for obvious reasons.
Also Misc proposals but that's more mundane.
I very much enjoy the PHD
I very much enjoy the PHD Shipyards website
http://www.phdship.com/
I've used these ships as a strong template for quite a while now. Don't know who they are, but I like what they offer.