I love having three monitors but in a pinch i can use one(like I do at home). I find the tool I miss the most and use all the time is Clipx. It's a clipboard buffer that lets me keep and paste the most recent 25 items. If I don't have that I feel like I'm coding with crayons, on an etch'n'sketch.

the other thing I can live without but prefer not to is music. Nice to listen too, and effective and drowning out background conversations...