If everyone else WASN'T going to die too...
I'd make a thread on here, telling everyone I am going to die the next day, and all the sigs I owe everyone will have to be carried on by the co-owner of Weasel GFX (wait, he quit, so everyone will have to get their sigs from someone better than me (a lot of people)).
Actually, I'd probably go tie up some loose ends, tell the girl I had a crush on... well I had a crush on her, try to master the Ballet kick before I die, try to to finish up the last chapter of my fanfic, try to read the last Harry Potter book, finish Final Mix (hopefully it comes out and I get it before I die), write out a will (the PS2 is pretty much obsolete now, so I don't know if anyone would want it...)
I'd also give my savings to my family, or to my church, or the youth group since they could always use some donations. I might eat a lot, at my favorite restaurant, and I'd probably have one last religious debate with my friends right before I died.
I'd tell my brother I was sorry for times I've been hypocritical, I'd play one last imagenary game with my youngest brother, I'd say sorry to my sister for being a little short with her sometime, and I'd say sorry to my parents for doing some bad stuff.
But then we'd get over it, and I'd... I don't know, have a party or something...
If every one else WAS going to die too...
Bowling?