This is a follow up to this closed question.

I open a random page, such as something on arXiv at 8:05 p.m. EST, and I see all these dollar signs, and I sigh and I wish that I could see nicely formatted math formulas instead, just like on MO. Is it possible? Can one write a Greasemonkey script to apply jsMath after the fact even if the page authors did not think of it? A Mozilla Firefox addon?

Please share your solutions. Seeing like this is an active community of people with similar interests, I am sure that hundreds or thousands of mathematicians would benefit from a solution.