Only thing I really need to be productive is one screen with 1920x1280 resolution. Anything less and I find myself scrolling more often than doing actual work. And one with a decent screen refresh rate. Too often I looked at a screen where a co-worker mentioned an eye strain and I could see it flicker - less than 60 Hz. Especially in the old days of CRT monitors.

Other than that a screen capture and edit tool is nice but Paint will get the job done sufficiently in a crunch.

Oh, and my little (private) laptop just to listen to music to zone in when I need to do any stuff where I need to concentrate.