From time to time I like to writte some short stories, mostly science fiction. Now, there is a competition of short stories here, and I will send a couple of my stories. And something came to my mind here on chess.com there are thousands of people, someone has to have a good ideas. So, I like to hear your ideas.The topic is Apocalypsa. Don't send me ideas which are aleready published as novels, stories...ect. I aleready cheched many sites like 12.12.2012 etc. Thanks.

I wouldn't bank on it!

 Why do you think that??

Most end-of-the-world scenarios deal with:

1. a catastrophic change in the physical environment: floods, pestilence, infertility, ultra low or high temperature, famine, nuclear holocaust, loss of viral/bacteriological immunity

2. another species becoming dominant e.g. super humans, intelligent plants, large insects

3. intervention by an outside agency e.g. alien invasion

4. shenanigans involving time travel

Generating a new twist will therefore be challenging.

excelent, all of this are ideas i can use. Most of this ideas i have thought before

Could you write a short story in which ALL of these things happen simultaneously. That would be unexpected.

No all of this in one story! These are ideas for at least 10m stories.

Precisely. 10m stories that have been written before. I know of stories that deal with 1 or 2 catastrophies. Yours would be the first that dealt with 10 or 12. But you'd have to keep it credible.

A very modern idea is the flash mob. What would happen if everyone in the world jumped in the air at the same time - or simply clicked their fingers? 

Zombies, zombies are always good. I sometimes write short stories; but they mainly dwell in the realm of Horror. I still have some half-decent ideas, better than his anyway:
http://www.youtube.com/watch?v=gLrxdkStd_U

Maybe it could be if Alchemy was true, and someone came along and began to take over the world with; an evil Dr. Frankenstein maybe.

Zombies.

The LHC [Large Hadron Collider] created a sub-molecular black hole, and eventually grew to a substantial size, enough to remove part of the earth.

Zombies.

EDIT: Maybe something to do with deep space exploration, what could possably go wrong?

Zombies.

What about if the sun dies out?  I don't think humans would survive that.

Thanks for the ideas. Alchemy is good, but I like to use it in stories as something good not bad, thought  it can be used for purposes of story and other way. I thought of artificaly created black hole. That is very good idea, too

A couple of alien safe-crackers need the combination to a safe in a another dimension. The combination is in terms of between 2 and 32 objects shaped suspiciously similar to chess pieces and arranged on an 8x8 grid.

The safe-crackers don't want to try out all the combinations themselves. So instead, they get some world (earth) hooked on chess, wait until electronic websites like chess.com come along, and then monitor all the games. They transmit an image of each position onto the combination reader at the intergalactic/transdimensional bank, and go away to make a cup of tea until the unknown position is reached.

That's creative and very elaborate!  

I hope they have enough of tea :-)

This where it starts to get interesting. They run low on tea so ... they go back in time and plant the secret of tea-making in some ancient earth culture.

What if the Earth got a new moon? What would it do to the tides, the philological aspects to humans; there is more likely to be a crime if there is a full moon. If it was large enough, maybe it would effect the gravity here on earth. Or maybe we could use it to hop to Mars, or Venus; thus bringing the travel time down, and increasing space exploration.

 This is good one. But in a story have to be explained how Earth got another moon. And it has to be a real good and believeble explaination. Any ideas of that?

An asteroid, maybe a comet, or just that the people wanted one.

If it was an asteroid, then it would to have to be coming from behind the sun, most likely from the asteroid belt. it could have circled under the sun, but then it would eventually crash into the moon, unless it was further out than the orbit of the moon. Then you could use the speed as an excuse for not being able to create a good counter-measure.

The comet would work if it was sling-shot off of Mars, then came into Earth's orbit. Some of the problems is that it would be easy to detect, and that it would spray ice onto Earth, and Earth gets cold.

The third choice is that people went nuts and wanted a new moon, not much beyond that.

Pick what you want, I personally think you should chose the third.