Someone's gonna say, "Let Cell have the Tri-Beam attack, since the Cell Jnr.s were able to do it!" Might as well be me.
When Cell fought Goku, he used a technique I haven't seen anyone mention. I don't think it has a name. It looked like he was about to fire a generic beam, but instead of the one beam firing forward, it split into around six separate parts. These six parts went in different directions, but homed in on one spot (where Goku was floating). I'll try to draw it, looking at them from the side:
...........---------------------------------------------------
........./ ------------------------------------------------....\
........*..*..........................................................*...*
..............------------------------------------------...............
.........G*...........................................................*C
........*..*...........................................................*....*
........\..-------------------------------------------------..../
..........-----------------------------------------------------
G is Goku, C is Cell, and the asterisks are the "heads" of the blasts. The centre asterisk is actually two - one at each arm.
What would this be useful for? Well, if someone was floating there blocking, you could quickly fire the split-blast off: since it hits them from angles above and below, they wouldn't be able to block it, even if they saw it coming. If you don't want to get caught in a PS, this attack's ideal for hitting them without them hitting you. It's a heckling move, designed to catch people off-guard and wrong-foot them, like Piccolo's scatter shot and Trunks' burning attack.
It would be a little stronger than a generic beam, and as such, each blast would have roughly a sixth of the damage. They'd be non-attached, like a bb or ki blast. They would automatically home in on the crosshair after a second of being fired, like what happens when you press alt-fire with Piccolo's scatter shot.