If you want an exchange without accounts to exchange cryptocurrency on the fly, you can use shapeshift.io. I have used it and it works like a charm. Check the video for a step by step tutorial.
There are many different ways to secure a blockchain. Some cryptocurrencies have a proof of work consensus, where extensive calculations are needed (mining), to secure the blockchain. With proof of stake, the amount of coins, residing on an online wallet have value to be selected more frequently to confirm transactions.
Pinkcoin is a proof of stake cryptocurrency. This means, that the wallet software secures the network. This is done by leaving funds in the wallet, and keep it on line. See more in the video.
Smart contracts were first released on Ethereum network. Other cryptocurrency networks, copied the smart contract functionality. So, it is important for the cryptocurrency user, to know about them.
Many people find out about Bitcoin nowadays. So, there is a great demand for information about getting involved. In the video you can see one of the many ways to buy Bitcoins. When you buy Bitcoins, you need a wallet to keep them. Online wallets are easy to use because you can have your Bitcoins available. StrongCoin is a good solution, because it is a hybrid wallet, that encrypt the private keys with your password. So, you are the only one to have them and they are derypted on your browser. See the StrongCoin Wallet