Being a person of minimal will power, the advertising for the Nob won me over.  http://nobcontrol.com/
 
I have to say - I love this little booger and using it within SPLAT.  I have my X-Touch controlling my channels, my Console 1 controlling the channel strips, but anything else meant either doing an Automap or creating an ACT.  
 
The Nob is so simple. Two switches that control the type of thing you are adjusting, and a big nob for doing the adjustment.  Position your mouse over the control (lets say its filter cutoff on the Z3TA2 synth), make sure the switches are set for circular controller, and turn to your heart's content.  The big nob (knob) has a very smooth feel and has very high resolution.  
 
No drivers, no set up, just point your mouse and turn.  
 
I have mine set up for my left hand and my mouse in my right.
 
While creating an ACT template or an Automap gives you something permanent for that plugin next time, this is immediate.  
 
It is a bit pricey, but it really makes fine adjustments so much easier.  Aint she cute?
 

Gotta admit I would love one of those. 
 
But $200? Nope!

I swear I just saw this thread.
 
EDIT: I did-
http://forum.cakewalk.com/The-nob-thoughts-besides-price-m3635139.aspx#3635139

it's not bad, but I wouldn't pay $200.00 either. 

Hi.
How do you find using it with your left hand works for you? Does it feel a little weird / cumbersome? I fear that..
Does it feel intuitive to switch between horizontal and vertical mode, or linear and circular mode?
Did you get a chance to test the "hold" function of the different modes? Does it feel "natural" to do that?
As you might tell, it's not my 1st time hearing about it  Or wanting it  
All the best.

Get yoursel a focusrite forte , you will have this and an exellent sound card lol

zargg
using the nob with the left hand and the mouse with the right is natural.  I have to position the mouse over what I want to change.  I seem to have settled into that pretty quickly.  I have my mouse, my computer keyboard and my nob basically in line from right to left.  
 
Yes it is steep.  But the operation is smooth and the simplicity of operating is phenomenal.  
 
 

As musicians I believe we all share a form of ambidextrous.
I am left handed but have always used my mouse with my right hand.
this would later prove beneficial working with control surfaces. Using my strong hand to dial and right hand to mouse.

chuck
My arrangement is (from left to right)
X-touch (on a tilted stand)
Nob
Computer Keyboard and Music Keyboard (front to back)
Mouse
Console 1.  
 
They are largely symmetrically spaced.  My left hand has a similar number of duties to my right.  The ergonomics are good, but not perfect.  The X-touch is a tad far away. I have to have a light over the console 1 as I tend to play with the overheads off.  
 
But it is about the best configuration I have deployed in the last 20 years.  
 
I mainly play (if that is what you call it) guitar, so the setup falls short with my left hand since it is holding the neck of my guitar.  Fortunately, I can hit R on the keyboard and get a take.  Cntrl Z is a reach though for my right hand.  Now if I could just not mess up as often!!!
 

space_cowboy
chuck
My arrangement is (from left to right)
X-touch (on a tilted stand)
Nob
Computer Keyboard and Music Keyboard (front to back)
Mouse
Console 1.  
 
They are largely symmetrically spaced.  My left hand has a similar number of duties to my right.  The ergonomics are good, but not perfect.  The X-touch is a tad far away. I have to have a light over the console 1 as I tend to play with the overheads off.  
 
But it is about the best configuration I have deployed in the last 20 years.  
 
I mainly play (if that is what you call it) guitar, so the setup falls short with my left hand since it is holding the neck of my guitar.  Fortunately, I can hit R on the keyboard and get a take.  Cntrl Z is a reach though for my right hand.  Now if I could just not mess up as often!!!
 

Might be a worry for me 
I wish there was somewhere to try this before buying it...