I really like the idea of Freicoin. They take a 5% demurrage fee is coins are not circulated. This solves one problem currently seen in Bitocoin, which is the fact that many are simply speculators selling and buying as the price ebbs and flows. There is one clear problem with this, however, which is the fact that there really isn't anywhere to spend one's Freicoin.
I think Litecoin is clearly the best investment. It seems, recently at least, to be on Bitcoin's coattails, rising and falling as Bitcoin does. Once either Gox or Bitstamp adopt Litecoin (which would seemingly mean that Coinbase would follow close behind), it should cement itself as a great complement to Bitcoin.