Here are some of the web banners created and contributed by Mozilla Taiwan's community members,
By roytam1,
specified with the license: http://creativecommons.org/licenses/by-sa/3.0/deed.zh_TW
By rail02000,
specified with the license: http://creativecommons.org/licenses/by-sa/2.5/tw/
By 不惑仔Boohover,
and one with transparent background,
For Chinese readers, here comes the rest of the relevant discussion thread from Mozilla Taiwan:
http://forum.moztw.org/viewtopic.php?t=19715