Im a big fan of the Faenza Icon Set available to Ubuntu users. One pet peeve of mine is the "new message indicator" icon in the Faenza icon set. If a new message comes in from Gwibber or Empathy many times I will fail to have seen the icon change and alert me of a new message because of the grey color. Its really not much different compared to no new messages.
As you can see in the photo, Ive taken the green new message indicator from the default Humanity icon set and plugged it into the Faenza set so I can see when a new message comes in. Its easy to make the change.
You will need to go into sudo mode to make these changes. When doing so, be very careful not to change anything else! Bad things can happen. OK, ready? Open a terminal (applications>accessories) and type or paste this in...
Navigate your way through the "file system" to the directory:
Copy and paste the "indicator-messages-new.png" image below into that folder. Do not change the name of the image. It will overwrite the icon that is there. Right click the image now and check the permissions so the image is set to "read and write" for both owner and group. Now close the terminal and nautilus and you should be ready to try it out! If it works correctly, it will look like the image above.
Right click and save off this image:
This was meant for the Ambiance theme using Faenza icons. You can also make this work with the Radiance theme by doing the steps above and placing the green mail icon in a slightly different folder...
One final note. If you have the Faenza icon set installed via PPA, you will need to redo these steps any time the Faenza PPA has a new update.