Target sells a very nice $12.99 GE mouse with two scroll wheels, one for horizontal scrolling. You might find, however, that the horizontal scroll wheel does not work in Firefox. The mouse is manufactured by Jasco under GE licensing, but it is actually a ripoff of this A4Tech mouse: WOP-35. Even though Jasco has not released updated drivers for the GE-branded mouse (their drivers are also ripoffs of A4Tech), the much newer A4Tech drivers work great (see link above).
