Questions about the BatchPCB service
Everyone else already mentioned search. But think about community design. Lets say every board includes Eagle files - pcb and schematic. Someone else could modify it and upload a new improved version. Boards/circuits could be designed by the community, iteratively. When browsing a board you could browse its offshoots/variations. Then other basic stuff: ratings, "it works" (like a thumbs up) or "it doesn't work" flags. "Most popular" "new" etc. And of course comments/reviews. Interactive/iterative community design would be pretty cool.