Slingshot were the first to bring on the "flex" and just about every company has an option for flex (or will have one)
hybrid watson and melissa's board (for the ladies or smaller guys) are the only "hybrids" boards that have significant flex AND noticable bottom features
the humanoid boards might count as hybrids too
sine wakeboards flex good too, but are not designed for rails, and i think i recall them designing a rail specific board, but it is not out yet?
ronix is bringing out the phoenix project. hyperlite was testing one. and LF i think will be adding some more hybrids to their line. that watson hybrid i bet will get voted number one board this year for the sales and reviews it has gotten