Actually a lot of the services that are now "big" existed already for a long time.

I still can't believe that back in 2001 we have been building something like a german Netflix.

Also my colleague who sat right next to me thought it would be a great a idea to have something like youtube for music in 2002 (Soundcloud) And he actually had a working service but he gave it up :)

Ideas are a dime a dozen, execution and luck are what matters.

Twitter in various forms was done about 5 times (that I saw) before the Twitter came up. Quite a few social networks predated Facebook.

I proposed a user-edited online encyclopedia in 1996, while working at the New Scientist. Everyone agreed it would never work, so the idea wasn't pursued.

Two years later, Everything launched, a year after that, H2G2, and two years after that, Wikipedia.

Ward's wiki launched in 1995 (or 1994, depending on how you count), actually:

http://en.wikipedia.org/wiki/WikiWikiWeb

There was "Community Memory" in Berkeley in the 70s:

http://en.wikipedia.org/wiki/Community_Memory

Don't forget timing. Netflix and Youtube probably wouldn't have been successful in the early 2000s just due to bandwidth limitations.

Didn't Netflix have what every other service was missing ? Netflix had a deal that they could stream whatever they had on DVDs for a fixed price. So they had boatloads of streamable content, which was the major stumbling block of everything else.

Music and video services have been entirely about the licensing, not so much the technology. Remember Napster was launched in 1999.

umm... not so much. Youtube was already a roaring success with user generated videos (which included lots of dvd rips, tv captures etc. etc.) before they started engaging with hollywood on a legal basis.

Yes, and their great success was in not getting shut down entirely (Napster) or soaked with prohibitive licensing fees.