All you have to do is make "donation" to them to have it listed from all indications.

Or, as in the case of Leafcoin... You get a few big holders to sell the coins back and forth to themselves at a minor loss (eating the fees) for a couple days. This of course makes the volume go through the roof, you then spam "we are doing 1000 BTC a day volume on market xyz" all over cryptsy's twitter. BigVern starts foaming at the mouth and bam, your listed. This worked brilliantly for them.

It seems like the coins that refuse to "pay to be listed" don't make it to Crypsty. DGB is a prime example. They have done everything right, have active dev's, great community, etc...But they refuse to pay to be listed anywhere. Hence, 15 shitcoins have been added, while they wait.