How are transition elements used?
Rather than try to develop a huge list of applications, I will direct you to a very useful website...
I could hardly scratch the surface of applications for these very useful (and in many cases, very common) metals.
Instead, you should check this website:
When you click on an element, you are whisked away to the Wikipedia entry for that element. There, you will find an entry in the list of contents called "Applications". There is an abundance of information for you there.