So I'm sitting at my work computer...(rodent related)

Um, I don't think I would be so calm!!

I don't have any thoughts on how to get rid of them.  We had them in our old office building, they would pee in the printer drawers.  ICK!!

We did the old fashion mouse traps, one got away, minus a leg.  

Oh, darn, I'd say "Hi" and bring it a jar of peanut butter, feeding it awAy from my desk.

You could buy one of those sonic repellers you plug into an outlet.

What georgiapea said

I hate the thought of various types of traps and poisons BUT there is never only one innocent little mouse, remember. Another unpleasant issue is that mice and rats are "incontinent" in that they pee on the go, wherever they are. Poo too. Often. Those little pellets and the pee smell are often noticed before any little faces peer over the edge of a desk.

Good luck!

Says the lady with a giant rodent on her neck.

I probably would too.  At work, when we had mice, I caught them and released them.  I did the same with spiders and other creatures that happened to venture into the classroom.  It was good for kids to see that there was an alternative to decimate the living creature into the carpet.  It would usually be a girl who would grab a cup, slide paper underneath it (or even let it crawl on her) and walk it outside to freedom.  

Awww Mr Jingles is looking for a friend. I’ve read people use dryer sheets in their travel trailer to keep mice out after winterizing.

None of the 'nice' remedies ever worked to keep mice out of our camper over the winter--the little jerks made nests out of the dryer sheets and peppermint-oiled cotton and climbed happily over the steel wool lining all the wheel wells! And as my dad likes to point out--if you've seen one mouse, there is a whole big family that you haven't seen yet . . .

We had a little exploratory party come into our home once--I don't have anything laying around on the floors where they can easily hide, so we knew within a day of the two little guys arriving that they were here (googled mice and found out how many little poop pellets one mouse makes in a day, lol!). After both were dispatched, I bought several of those little sonic plug in devices and put them all over the house. We also have two dogs who have arrived since then. Not sure if it is thanks to either of those additions, or something else entirely, but no mouse has crossed the threshold since.

honestly, I'd tell management, and expect them to do something about it-- but then again, I work for a company that makes food and nutritional products, and ANY type of contamination is a no-no for us. We have a pest control company come every two weeks to inspect, and there can't be ANY gaps / ways into the building at all; if anything like that is found, the maintenance department fixes it.

Could you catch him with a humane trap and let him go somewhere else? We've done this at home every since dd was old enough to protest killing them. lol. 

Your story reminds me of one day at school...I was there early because I was subbing for someone I'd never subbed for before and I wanted to be sure to have enough time to read over her plans. I was walking down the hall when suddenly there was a blood-curdling SCREAM!!! Omg, I thought something awful had happened. Teachers came running out of the classrooms, the custodian came running... thank God there were no kids there yet! It was the librarian who had opened her office and there sitting on her desk was a tiny mouse. She is apparently deathly afraid of mice.   Took 20 years off my life just hearing her scream. Not sure she's ever lived it down...people tease her for being so afraid of a tiny mouse. She takes it with good nature because she admits that it's silly to be so afraid of such a tiny thing. But now when she goes into her office she makes a LOT of noise doing it. lol