Here's an idea -
I mentioned already that it is possible to convert any altcoin address to a MemoryCoin address for tipping.
It would also be possible to create a dice service that accepted bets in one coin (say BTC), and made payouts in another (say MMC) or vice versa.
If there were a payout that had 100% odds - (say minus a 2% house edge) it works just like an exchange.
The exchanger doesn't need to keep the funds online (doesn't need to reveal his IP - just needs liquidity in both currencies) so it's easier to operate.
Users don't need to trust the exchanger much, because they can exchange over time rather than all at once.