Bitcoin has been popular, but Namecoin isn't too popular even though there are diehard advocates. But because of the Bitcoin increased in popularity and also in value, there are some forks of Bitcoin starting to appear, ixcoin and the i0coin. Both was popular for a while before fading off. They were being revitalized because of merged mining, something that had also happened to Namecoin. But the value was far too low to be considered Bitcoin competitor at all. Miners mine them because the mining pools had merged mining for these.
Why has Bitcoin miners turn to mining pools? Simple reason was it was taking far too long to solo mine due to the difficulty. Mining pool allows for the pooling of hashing power so that you can some Bitcoins regularly rather than to wait months for a Bitcoin block. I will be discussing about Mining Pools in the subsequent Blog Posts.
With regards to ixcoin and i0coin, there is some interest in the naming. It seems that ixcoin was premined and there was some objection that the creator can profit from the premining. i0coin as in "0" was to say that there is no premining and to act as a competitor to ixcoin and serve as an objection to the premining. Though I would say some premining may be needed as you really do need bounties to start the ball rolling for the coins you are developing. You may need an Exchange, you may need mining pools. By providing bounties for such development, it hasten the progress of the coin development.