Basically any mouse that has a ton of buttons on them, the so far mentioned Razer Hex and Naga would be good options (pretty much any MMO gaming mouse would). When it comes to mice, Razer are a very respectable brand (The last two mice I have bought have been Deathadders, best mice I'v ever used). Might be a bit off the norm, but the Razer Orbweaver could be a good option.
It isnt a mouse itself, but the idea is that for games you could set hotkeys to the Orbweaver and you remove your hand from the keyboard entirely to it, where there its more "button dense" and more ergonomic.
http://www.razerzone.com/au-en/gaming-keyboards-keypads/razer-orbweaver/
If your job is pretty much copy/paste or other repetitious tasks it might be a good option.
Corsair is a pretty respectable brand, everything they make across PC hardware is good quality.
The reason why your not seeing names like Dell and HP on products like these is because what your looking for is typically what gamers want, and they dont cater to that market. Besides, Dell would struggle to convince enthusiasts that their stuff is any good, the only Dell products you will find recommended on these forums is their monitors (which are actually very nice) but are again intended for a professional audience.