First things first: internet famous doesn't mean real world famous. Now that we have got that right, here are some ways people have become famoous on the internet.

Basically it amounts to being the most quirky person on the famous site of the day:

If Twitter is the flavor of the second, set up a topical/parody Twitter account (e.g. fake steve jobs, fake AP style guide, hitler tweets ww2...)
If it is Facebook's day in the dying Sun, set up a quirky/fake/dubious/controversial page facebook page, post quirky things fast, before Facebook turns you off.
If you like blogging, unlike other lazy types, you can blog about wearing one new dress a day for 30 days/365 days (or a new recipe a day) - 'X' a day types really do well.
If you are into videos, and can shoot okay mobile videos, do a quirky take on a popular TV show format - e.g. I like 'My Drunk Kutchen', where a cute, seemingly drunk girl try to cook something for the day...
And so on.

Other way, involving all or at least one of above, plus a real offline activity, is the 'stunt' - e.g. pasting a Facebook page print out on Mark Zuckerberg's face.

So, what have we learnt here?

The formula seems to be this:

1. Be interesting, quirky or otherwise notable
2. Have people notice that and talk it up a lot
3. Get media attention and don't shrink away from it
4. Repeat

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