I made a texturepack that I liked. It doesn't change much, just the sun, the moon and the nether portal. if you load it up in single player, it works great. If you load it up from your texturepack directory and go on a server, it works great too. But if you make it a server texturepack, you get all kinds of blocks with wrong textures and everything.

the first picture shows what happens if you get it with server textures, so the game downloads it automagically for you.

the second and third picture show what the texturepack changes and how it behaves if you load it from the texturepack directory