I use the Kensington Pro trackball. It's expensive, but since I do a lot of work with the computer, I decided £100 would be an investment (except I managed to knab a completely unused one, for £50, on daBay).
Trackball is the instant way to eliminate RSI if you do a lot of computing. Your right hand is more important to you and irreplacable than £100 quid, so I'd say it's a requisite for anyone spending a lot of time at the PC, doing fiddly edits.
Next up, I use a Wacom tablet (the same one I use for Photoshop) for painting in clips in a sequencer. It's a very nice way of doing things. It's fast and accurate. When it comes to mice, I believe the trackball (that's a proper one - not a little excuse for one) is the industry standard for pointing around in DAW software... Or any professional software, for that matter. It's far better for accuracy, precision editing and above all, comfort.
Plus, you can set up to hover over a record button, for instance and then click it, without having to check your pointer is still on the button.
With a decent one, such as the Kensington, you can customize the buttons. This means I can click once to drag and then move sliders up and down, with just one finger. Feels like you are moving a real slider. Lovely!
With a bit of practice, you soon get used to it. The minute you try someone else's pointing gear, you realise how crap the common mouse really is.
Mackie Control Universal, Contour Shuttle Pro and footswitches...I like footswitches. A wireless mousie when I hafta
I reckon that's even better. £££ no grind, I'd love one.
Dr. V