What I'd like to see is a script to change fluids into either blocks or other fluids if they are touching a specific block, such as water turning into brine if it touches a salt ore block (with the option of changing the salt ore block as well), then changing the adjacent water into brine in a chain reaction, meaning that those salt blocks on the bottom of ponds would turn the ponds into brine.
To prevent this from turning whole oceans into a different fluid, this would have to limit the chain reactions to only occur within a certain distance from the original block that triggered the first change.