ok how about these:
Riot Blade - Terra
Spin Edge - Celes
Tiger Break - Sabin
Mirager - Locke
Royal Shock - Edgar
Star Prism - Relm

they are all i can remember right now, although i must confess spin edge is the best looking, to do a desperation attack you must be low on health and then i think it is a 1/16 chance to do it when you choose "Fight"

What was Shadows one again? i think Strago and Relms ones involved something like STar Prism and Soul Saber or Soul Prism and Star Saber, if anyone wants a movie i have of all the desperation attacks tell me and i can send it ok?