putting something like:

body,td,p,li,pre {
    font-size: 16px !important;
}
[download]

in the user stylesheet on my user settings page seems to catch about 90% of the text. with a few more rules, you could probably get the rest of it.

the <font> tags should definitely go though. they're sooo 1996...

update: this:

body * {
    font-size: 16px !important;
}
[download]

catches every bit of text on the site i can find. (tested in mozilla).

anders pearson