Send the coins back to yourself using a mix. No one, not even the sender, can tell what you did.
Probably best to wait a little while though, since timing can be used make inferences (though never with certainty) about which transactions are related.
Hm, probably most secure would be using an in-between account, I guess.
Could be accessed with TOR, once it's supported.
Not nice, but effective. Or do you think it is overdone?
Using an in-between account doesn't add anything, because each transfer using a new one-time key pair.
As far as anyone else can tell (non-participant to the transaction), every transfer goes to a new account. Since you are the only participant when sending to yourself, no one else can tell.
The complicating issue is lack of coin control in the wallet currently. The only way to ensure that the coins are resent is to use a separate wallet.
