Wait, entropie, there is an easy solution which you might enjoy (I've been thinking a lot about the issue, obviously): since this crisis is a balance of payments crisis, due to the differential in competitivness between german and italian, french, greek firms and the presence of a common currency that cannot appreciate, average german salaries should be let free to progressively rise, so that germans can buy more products from italy, france, greece etc. (basically another version of a monetary appreciation) and restore equilibrium in the balance of payments. This situation would (slowly) solve debt problems, since usually excessive public (or private) debt is a direct consequence of a skewed balance of payments - which can only happen when currencies are manipulated (see renmibi vs USD).
Of course this would not solve the interest rate problem which has caused a boom-bust cycle in Spain, Ireland and Greece while the EBC was keeping interest rates low because france, italy and germany were not growing. In my honest opinion the Euro is not an optimal currency area and it needs to split, the other option would be a structural convergence among all the economies which may or may not happen, but which will require at least 30-40 years and large transfers from the core (the core being central-western france, benelux, germany, northern italy, nort-eastern spain) to the less competitive periphery, a policy which is not politically viable imho.
Anyway there are already two central banks (ECB and EBI) and they act very similarly to the way you have described. The ECB lends relatively "free" money to banks which in turn lend to businesses, while the EBI lends to private companies and individuals whose projects are considered viable.
Well the real problem is that you cannot force growth, the government literally does not have a clue as to how promote growth in industrialized countries. So what happens if you enforce a balanced budget in a recessive economy? Such economy spirals into deeper recession, just like it's happening in Greece and how it will soon happen in Italy, which will likely record a -3% GDP in 2012 and an exploding budget deficit.Sooner or later the EU needs to start rigidly enforcing the agreed growth and stability pact: annual government deficit to GDP and gross government debt to GDP levels. In exchange for doing so, the richer nations have to either back poor countries or quite literally throw them out of the euro-zone.
IMHO a good pact would be: force a balanced budget when growth is zero, however when there's a recession ongoing (say GDP going down more than -0,5%), let the budget deficit float down without imposing any punishment. Conversely, when growth is above 0,5%, punish countries that incur in a budget deficit.