I did some research on sending money to Japan and I came up with some interesting results. For large amounts ($10000 and up) I listed them in the most bang for your buck, with the amount given, less fees and dollar to yen spreads, assuming a published 109 yen to the dollar rate for $10000.:

1. Post office money order, 1074944 yen
2. XETrade.com, 1069985
3. Visitor ATM, 1060000
4. Direct wire from your bank, 1059975
5. Ikobo.com, 1057150

Each of these has their advantages and disadvantages

1. Post office money order: $700 max per money order, $10000 max per day
2. XEtrade: 2 week sign-up process
3. Visitor ATM: 50000 yen per day max withdrawal
4. Direct wire from bank: Might be charged excessive fees on both ends
5. Ikobo.com: max $1000 per card, max 50000 yen per ATM

Anybody have additional options?

If your sending that much, bank to bank wire transfer is probably the best way to do it. Usually the rates are set, and don't vary with the size of the transfer.

Ikobo would be $5 + 3%, plus there are withdrawal fees. So just sending the money, $1000 at a time, would cost at least $350.

I use moneygram. Fees are very low.