yoga poses / stretches for tight shoulders/chest muscles

hi all,

i have really tight muscles in my shoulders / chest. i find that i am hunched over, rounded shoulders, and really tight across my chest all the time. my posture is shocking and my breathing is now getting affected too - shortness of breath etc. i work on a computer, so i think this is a classic symptom of hunching over my screen.

can anyone recommend a few yoga poses that i can do (through out the day, at work, or specifically when feel tight) that work specifically on opening the chest up.

I'm thinking backward bends, the camel, cobra... those type poses would help? but which is best specifically? and are there any others that you thing might help, or may be even better for this type of problem?? ideally i would be able to do them at work, so the backward bends poses might not be ideal - as i don't think it would look too good in my office. lol

any advice would be appreciated.

thanks