What make a new coin "valuable" ?
How / Who establish its value vs BTC / LTC ?
How can be listed a new coin on sites like Cryptsy, Coinex, Bter then on BTC-E, Crypto-Trade, Bitstamp, etc ?
What make people to adopt a new coin ? I mean, look at DOGE.
The persons involved in launching new coins shouldn't be worried about the "value" factor ?
I'll try to answer some of your questions
What makes a coin valuable is really the perception of the community about it's value along with the various features a coin has to offer. I mean coins with innovative coins like Nxt (Guess we all know that one) or Vertcoin (Asic/GPU resistance) will onviously be seen as coins with a future since they are offering something new to the scene of cryptocurrencies.
Establishing it's value vs BTC/LTC is based on numerous factors, some of them are the price the cummunity is willing to pay for the coin. Another factor is the amount of coins in distribution, a coin 10 billion coins in circulation will obviously be worth les as a coin with 10 million coins and the same features.
Getting listed on exhanges is about getting votes on their forums and establishing a trade volume, this is because a coin needs to be profitable for an exchange aswell (trade fees).
Another factor in getting listen on an exchange is, in some cases i might add, bribing. Some exhanges are willing to take coins on their website in return for a share of the devolopers/community's coins.
Adoption of a coin is mainly a community thing, when certain people spread the word about a coin and get more people involved in a coin it'll be an upward trend from that point on. Those new people will also tell their friends/families about the coins and before you know it you've got a flourishing community around your coin
However it's also got to do with something i mentioned previously, innovative features. when a coin is launched as 'another clone' it'll be alot harder to find adoption for your coin as when you start up a whole new concept for a coin.
Hope this helps
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