You can then continue your turn. This creates a steamroller effect that often brings about the end of the game.
Thanks, in spite of what my post said, that is how I thought it should go. Re-reading my post now, when I'm not bleary-eyed at 1:00 am after a multi-hour Risk-fest, I see that I wrote it wrong.
Our game went longer than necessary because the others insisted you had to wait uintil your next turn to use the armies gained from your opponent's elimination.
Is this explained in any other version's rulebook? I really don't see it in mine.