I would like to know how to handle the following situation.

I have been at my place of employment for 10 years in the same position. I have interviewed for several promotions, and have received none. My boss alwasy tells me I am an excellent worker and a great asset to her team, but always chooses others to do special projects or for promotions. I have been dealing with this for several years now. I have tried to take it in stride, but it is really starting to wear down my morale and I do not feel like part of the team. I have no desire to enteract with the team, and have to force myself to do so when required. My boss seems to have chosen another team member to mentor and it seems that person gets all of the opportunitites that would help in getting promoted. This other person has only been with the company for a little over a year, and has less experience that myself. With the economy the way it is, I am afraid to really say anything for fear of losing my job. Any advice?