Yeah, that would be rather simple, at least if you base it on an existing project, such as bitcoin. Although, being a P2P network, you at least need a couple of people online and using it before it makes any sense, value or not

I don't really know about namecoin, haven't looked much into it yet, so can't help you there.

Regarding creating an alternative currency, yes and no. For someone technically proficient it would be pretty easy to fork the bitcoin source, make necessary changes and start a new whatever-coin with a new blockchain. Looking at it that way, creating an alternative currency is easy. But it depends on how you define currency. For most people, I guess a currency will only be a currency when enough people place value in it, to allow trading with a sufficiently large amount of other people. That's the hard part

The rule is ok, but when you want to reply it can be annoying