You can use an OP_RETURN transaction and embed up to 40 or so bytes of content that will be forever secured by the blockchain. The OP_RETURN output script should have a small value as the coins will be destroyed.
40 bytes is plenty for a date and a name.
Why a small value? Why not zero value? It seems like a waste of bitcoins to put any bitcoin value on the OP_RETURN output.
You can go to blockchain.info and send a comment together with the transaction, then it will appear forever next to the address you send it to!
You will need 0.0001 BTC to be sent + fee of course.
This is NOT correct. Any comment you add with this method is stored ONLY in the database of the company that calls itself blockchain.info. It will not show up in any other block explorer, and it will not be stored in the bitcoin blockchain.