Intelligant file search for firefox

I want to use a grep like search routine in firefox's search file dialogue i.e. I want to click on 4chan's 'Search' buttan and be presented with a field where I enter 'cat' and I will be shown a list of files that have the pattern 'cat' somewhere in the filename. Any ideas on how to implement such a feature. Better yet, does anyone know an existing firefox extension that is able to do this?

>>25

Tivial? Maybe I didn't make it quite clear that I want to use this tool from within the file dialogue. As it is firefox suggests foo-bar.jpg when I type 'foo', but I want it to do the same thing, when I type 'bar'. If this can be easily accomplished, just tell me how, okay?