Create mouseOver Description For your items/blocks

    /** Item MouseOver Test **/
    public void addInformation(ItemStack par1ItemStack, EntityPlayer par2EntityPlayer, List par3List, boolean par4) {
        par3List.add("Hello"); // The "Hello" bit is what will display Below the Item/Block name
    }
    // I think the following code is pointless but try it yourself!!
    public String getItemDisplayName(ItemStack par1ItemStack)
    {
        return ("" + StatCollector.translateToLocal(this.getUnlocalizedNameInefficiently(par1ItemStack) + ".name")).trim();

    }