Here's a list of MMO mouses. That is, mouses with more than 10 buttons, usually 20.
Razer Naga Mouse
Razer is the first to have created the keypad mouse, the Naga MMOG mouse.
At first i thought this would be the most stupid mouse. I thought that, some geek thought more button is better, so jam'd the mouse with cellphone number keys. The result would be very painful to use. However, from reading amazon.com's reviews, apparently it is usable.
After reading and watching many reviews, this is actually a very good mouse. Half of the buttons can be operated by touch easily.
When this mouse first came out in 2009, the number keys are not programable. They are simply the same as the number keys on number pad (so, you program the number pad keys instead). But with version 2 of driver, they are programable now! So, a mouse with truely 17 programable buttons. That's fantastic.
Left Handed 17 Buttons Mouse: Razer Naga 2014
And, if you are left-handed, or wield double mouses, one for each hand (as i do), this is for you.
Razer Naga Hex Gaming Mouse
Apparently, 17 buttons is one too many for some. So, Naga came up with a 6 side buttons version, the Naga Hex.
Though, some reports that the buttons are actually confusing to use, and prefer the keypad-like ones.
Redragon Perdition Mouse 红龙 灭世 鼠标
This one wins because it's cheap! About half the price of similar mouse, and the reviews are not bad.
The only issue is that it's biggish mouse, for large hands.
Mostly positive reviews on amazon.
UtechSmart Venus 18-Buttons Mouse
This is a new comer. First available on . Much cheaper than competitors.
see video review at UtechSmart Venus Gaming Mouse
What about wireless?
more photos, see: Razer Naga Epic Rechargable Wireless MMO PC Gaming Mouse
For a list of keypads, see: List of Programable Keypads.