Causality loops in time traveling stories all have the loop being closed in the past (causing the "You can't kill your Grandfather" problems), close one in the future (go forward to kill your grandchild).
And then there's the whole, "We can't pollute the time streams" mantra and meme. Screw 'em. I have a short story in progress (might turn it into a short short now, maybe 2000 words, I haven't worked on it in years though) where I deal with this in both directions (how going back in time won't pollute the time stream and create a "Sound of Thunder" like story plus going forward to create a new and better future, and it involves a whole bunch o' hand-waving stuff to make it work that I won't get into here - temporal-calculus, that's your only hint). Now, most stories (and I believe these are cliche by now, so don't do them) involve going back to stop some horrible problem of the past, like killing Hitler (although one story, I forget the name, does it a little better by rendering the Brown-shirt movement powerless by convincing the HIndenburg Government to take it seriously and keep them tamped down). I want you to really pollute the stream. How would you re-engineer the past?
And here you want to think fully. See, killing Hitler wouldn't change much. However, polluting the stream right at the end of WWI could destroy any chance of the Nazi and Fascism elements gaining power, or even thinking up those forms of government. See, to kill Hitler, don't assassinate him, kill Hitler's grandfather. Burn that line to the ground and then plow under the ashes. Don't poison the cup, poison the whole well.