I would like a new type of light. Many builds you have trouble that the glowstone doesn't fit in with the theme or the redstone lamps can't be powered. A new lighting block (not like a torch) would be awesome in builder's perspective. What it would be? I have no idea.
Consider running virus software or changing your skins back to default, if deleting the minecraft.jar file isn't working. And yes, updating will probably fix the issue.
