It can be done with greasemonkey if you have the patience (simple javascript), but I never cared to dig into it enough to fully implement it. I have had it working for a short period of time to remove some offensive image macros from certain posters, but just didn’t care to rebuild and maintain it after a hard drive crash. And yes, I did have it working for FR...
In certain instances ignore is a nice function, but ultimately I’d have to agree with the mods and Jim on this anyway.
LOTS of things can be done with a greased monkey if you have the patience.