David Vs. Goliath - Does it hold true?

Google recently launched MyMaps, which allows you to create custom maps with your own placemarks. This has sort of made websites such as Wikimapia and other mashups redundant. There is one another site called Picli, which is regarded the Digg for pictures. But, it shall not be too late before Digg introduce a pictures section as well, looking at the demand for a picture section on the Digg website. Then, there is one site I had talked of which helps in downloading YouTube videos. What if YouTube provides that functionality on their website itself? All these minnow websites have been treading on the thin line unattended by the major websites, and when one of these small sites start to get real numbers in traffic, these major websites crush the little threat that they hold by providing the very facility. It does look that the concept of David getting over Goliath is seemingly impossible in the case of internet. What's the strategy then? If you look closely, you will find some sites that have taken better to the idea of complementing big sites, and successful at that. What's the strategy here? Simple. Go through the Terms and Conditions of the site, and you shall know what areas the website does not and will not venture into. For example, YouTube does not feature porn. So, PornoTube makes a successful strategy. Most networking websites require you to be 18 and above. Maybe, a networking site for children should be a nice idea, though regulations and moderatorship are a gray area here. But, the point is that if you would want to replicate the success of major websites, dont clone them on a niche where the very site can be a competitor. Choose where they would not venture into and there is a nice chance that you hit the right spot.