Alternate cryptocurrencies are great, but please refine your ideas long enough and build a solid infrastructure. Don't be late on launch, have executables for all platforms + source code available, have a working block explorer, some currency exchanges (probably from YourCoin <-> USD / EUR), existing services (not necessarily anything big, but something for people to abuse their coins, poker for example) etc.
Have big enough starting difficulty so it will be more equal playground for everyone. Name your currency wisely. Encourage people to mine and test their services / setups on testnet, before launch to find any potential problems etc.
There's no need for a red carpet launch, only the source is needed. Bitcoin and Namecoin launched with just the source and are doing just fine. Namecoin doesn't even have an official GUI yet. Agree about refining the idea, having enough starting difficulty and a marketable name though.