I had an idea that if you built a structure out of enderstone or another block that could be added to the end, it could be made that enderman will not pick it up and cannot teleport through it. This could be useful as a sort of protective covering over a house. If ender stone is used instead of it dropping cobblestone when mined without an enchantment perhaps it could be made so that mining it without an enchenment could produce a 'dust' that could be crafted with other blocks so they will be 'enderman resistant'. They would not however be completely enderman proof: there is still a small chance that endermen can teleport through it (there is no chance when using plain enderstone). Layered levels of the enderstone dust could reduce this chance. The dust could also be placed manually like redstone.
Tell me what you think.