I don't like to say this, but the only logical solution is the one put forward (half-heartedly) by Sarkozy: let the ECB be the European FED, a proper central bank with full powers at European level, so that debt can be underwritten by Europe as a whole. The collective credibility of Europe as a huge market and productive force is unquestionable, so this would stop speculative moves and stabilize the system.
Unfortunately, Germany is currently led by a chancellor who thinks she's running a Bavarian village, and would rather try to save her cows into a "safe barn" than to stop the avalanche from getting into the valley in the first place. This makes it easy for US and UK media to fuel doubt in the Euro, indirectly boosting their own currencies and helping themselves to artificially-low borrowing rates.
And I say that as a UK citizen who will eventually benefit from this state of things (through increased public investment, or rather less ferocious cuts by the bunch of aristos currently running the show over here).