Pay Remarks allows simple plaintext.People sending coins can insert arbitrary strings of their choosing into the blockchain.Remarks can be encrypted with the public key so only the owner of the private key can read them.

I think it would be a really nice user experience for people to send messages, even if private, with their payments like "here are your FTC I promised, thanks for the beers". But for it to really work it would have to work on all wallets not just the QT client. I see the message could be useful to vendors as a cryptographic receipt system.

against spam and offensive links

There has to be a limit on the size of the message and the message should be included when working out the fee. I would suggest a much small payment level.If the length is less than 40 bytes,that would be 0.05 (FTC).If the length is less than 140 bytes,that would be 0.5 (FTC).

The disadvantage

there would be a message blockchain, if the miner wins they would have to extra work creating the message block chain. Also the extra network traffic, cost.

Also note that this would require a hard fork so that current clients would not be compatible with clients with messaging.

Add "tx-comment" in Blockchain, the code was easy . Your any ideas please let me know.Lets go ahead. :)