Here are some more examples:
Code:
        ## backquotes become apostrophes:
        gsub("`","'")

        ## backslashes become dashes:
        gsub("\\\\","-")

        ## slashes, question marks, carats, dollarsigns become underscores:
        gsub("[/?^$]","_")

That last one above shows one way to deal with characters you aren't sure about: enclose them inside square brackets and they are no longer special (except for backslashes, dashes, or a leading carat).