A Yellow rug would give this room a great pop of color. you could also add a couple grey and yellow throw pillows to the sofa to tie it together!

So you think the rug I have in mind is a good idea? i searched through many many rugs and I think this one would actually work..

That rug looks like it would work quite nicely with your gray chevron ottoman. But do check the colors together to make sure. It appears that you want to keep everything quite neutral. You may eventually want to add some color, but you'll know when that time arrives.
Carolyn Albert-Kincl, ASID

When that moment does occur, jpmcmahon was certainly right that yellow would look great in your room. Here's an example below.