No1 feature that Linux needs (after marketing)?
-Games of course! Until Prince of Persia, Fallout and Pro Evolution Soccer get ported to Linux, a good solution are Flash games.

Y8.com brings about 10.000 flash games that you can play from your Linux PC! It includes Action games, beat-em up, Fantasy, Flying, Racing, Shoot-em Up and many many more.
There are more sites with flash games, but I didn't find any which such a high amount. Googling for "flash games", will show more sites like this.
There are also Massive multi player browser games like:
- The bowser game portal: Site with many high quality browser games
- F1time
- Grand Prix Manager Online
- GP Manager Pro
- Ikariam (Select your language using the flags on top)
- Ogame (Space Empires game)
- Tribal Wars

The following are Role Playing Games of supreme quality and sense of humor. Even if you have a dozen RPGs in Windows, don't miss them, you 'll Laugh Out Loud(LOL) every time you play them!

So next time someone is hesitant to try Linux because he/she wants to play games, then Flash & browser games are the answer!