For the new tilesets that people are making you could include a small type editor which allowed you to produce a dat file for the entirity of the tiles in the png. and when its saved it could be uploaded to the server and set as a non client changable flag to the player at certain points. Also the file would not run if it was not d/led first or date / time matched servers or something nifty like that. Of course being it only small ammounts of data in the file it could be set to download to the client everytime it was accessed.
Also a function to call certain frames in a gani file for single sprite animations. Such as a person could make a bunch of single sprites in one gani and then call them by their frame. that would be good for some animations like holding a trophy then 2 trophys then 3 trophies just a small animation for effect but no having to download multiple ganis for every single small animation
Thats all i have to say for now as im stressed for time