Pokemon Gold and Silver, the sequels to Blue and Red are in production and if our sources are correct are almost in release in Japan or are already available there. They will hopefully come to America soon. Japan also has a 3rd Cart which is the Japanese Blue Version. The original Blue in the U.S. was actually the Green Version in Japan. The games are only different because in the 3rd Cart you can trade at different places. An example is that you can get Lickitung in the Safari Zone instead of trading for him.
Nintendo is also reportedly making plans for the next Zelda game. It may be for the Nintendo 64 or it could be for the next system Nintendo is building.