I found a kitchen timer that doesn't tick at Target. It's an Oster brand, brown with a circular dial, 60 minutes. It doesn't tick because it's battery powered. It doesn't ring but it beeps like an alarm clock. You can set the countdown time from 0 to 60. You might be able to quiet the beep by putting it in a drawer or covering the speaker hole in the back with tape or putty. I looked for a long time trying to find a countdown timer that didn't tick. It would be nice to find one that has an adjustable volume, too, but the point of a kitchen timer is to ring loudly enough so you can hear it if you're not in the room when it goes off, so I guess it will be hard to find one that's really quiet.

Any countdown timer that's mechanical will probably tick--I tried several of them a year or so ago and the ticking drove me crazy. I tried putting them in a desk drawer, across the room, but the ticking was loud enough that I gave up on them and gave them away.

You might also look into white noise machines. I have one from Sharper Image that has a countdown timer, and makes the white noise during the countdown. It's a travel clock/alarm clock combo thing--Travel Soother 20 Model 51601. I like it a lot--the white noise helps mask the sounds around me, and when the countdown period is done, it just goes quiet, it doesn't ring or beep. And you can adjust the volume of the white noise, when it's at its lowest volume it's really very quiet, barely audible. But when the time is up, the white noise just stops, so maybe that would be too quiet. The countdown time can be set in increments of either 15, 30, 60, 90, or 120 minutes.
http://www.sharperimage.com/us/en/catalog/productdetails/sku__SI601TNM/catid__38055900/pcatid__4

Also, my cellphone has a countdown timer, very flexible, and I can adjust the ring volume. That's really the best countdown timer I've come up with. And another benefit is that I always have it with me. Maybe your cell has a countdown timer, too.

Good luck. I never imagined I'd have such a hard time finding a countdown timer, hope you find one you like.

Most lab supply companies sell (or give away) simple timers that count up and down. Try http://www.coleparmer.com/opproducts/lab_supplies.html for examples.

If you don't want the annoying beeps a mobile phone set to vibrate is the quickest solution

I picked up a Timex Ironman Triathalon watch that does interval timing and regular count-downs. It looks like you could set it to do the 10+2 with the interval setting, if that's what you are looking for.

I needed something always available to help me remember to check my blood sugar. The timer on my desk always seemed to go off when I was down the hall.

The thing I like about it is that I don't have to constantly reset the amount of time I want to count down. It remembers the setting between uses.

What amount of time are you wanting to count?

I have a small digital time, "Good Cook" seems to be the brand. I'm sure I must have picked it up at the grocery store. (Found it: http://www.amazon.com/gp/product/B0006MBUJ2/ref=nosim/102-0497708-7840957?n=284507)

It doesn't tick and has a very gentle little digital beep, which you can shut off with a touch of the finger. It would be easy to miss if there's a lot of background noise, but it might be what you want in a quiet office.

I'm looking to time a 10+2 dash as you suspected. I don't want to use my Ironman because I don't wear it to work (too many nicer choices).

Thanks for all the suggestions, I'll take a look at the particulars people pointed out.