I am one of those people who is not comfortable talking to others, especially when it comes to witnessing. But I have found something that helps alot in that area, and I think other "shy" people would like it too.
I have one (several, actually) of those little scrolling electronic readerboard badges, and often affix it to a purse or backpack, and have a Christian message on it. (My favorite is 'Jesus Died So You Could Live!')
I have gotten numerous compliments at church by people who think it's a wonderful idea. If I'm nervous talking to people, I just let it do the talking! And if anyone reading it wants to know more, they can simply ask!