a few i feel would be good to add-
i've also rated them with what i think to be their priority
~Spawners -High priority
~Dragon egg [not sure if this is already lockable have never tried]medium-high priority
~Pistons [nothing is more annoying than someone destroying one block and breaking your entire redstone creation]Medium priority
~Minecarts [from previous servers i know these things go missing a lot from transportation tracks]medium-low priority
~Ore blocks [diamond/emerald/gold/iron/redstone/coal]medium-low priority
~Glowstonemedium-high priority
~Nether quartz oremedium-low priority
~Diamond,emerald and redstone orelow priority
~Anvilsmedium-high priority
~Enchantment tableMedium priority
~Beds (i have lost my home many times from people destroying my bed)high priority
~Heads [of all variants]high priority
~Item frames [people like to steal items out of these 
]medium-high priority
~Daylight sensor [may already be lockable haven't ever tried]medium priority
~Redstone lampslow priority
~Leashes [if possible]low priority
Ok some of these I don't think are possible to lock, such as minecarts, dragon eggs, or item frames. If you live in town though, you can turn off the itemuse perm. Iron blocks, gold blocks, and spawners are already lockable.
