Have you seen the final four movies yet? Do tell us your opinion!

In around the world in 80 days he shows up near the very end where the main villain goes on a rant telling everyone that no one can stop him then after he says "you?" For the 3rd time then you'll see Tobin in a top hat and a mustache displaying a surprised look in his face. Keep an eye out and try not to blink. By the way he's not credited.

actually you could also count his autopsy and i think, when someone watch a videotape of him (the tape was filmed in the past, but the guy watching it is in the 'present' )

^^This. Pretty much. He's back in the flashbacks but that's it. Other characters are the main focus and he interacts with some of them all in flashbacks.
"I am the ultimate badass, you do not wanna *beep* wit' me!" Hudson in Aliens.

No, not at all, or else the following Saw's wouldn't have simple number titles. Tobin is in flashbacks and stuff.
But the end of Saw III is indeed the last scene involving Tobin to happen chronologically his death, obviously.

Oh right, so chronologicly, the ending of Saw 3 is technicly the last thing to happen in the series ?

^^Because it shows other things that he did around the time and shows how he's connected to the other people going through the tests.
"I am the ultimate badass, you do not wanna *beep* wit' me!" Hudson in Aliens.