Buying toxic assets is "nice" for banks, but solves nothing. Bailing out AIG, oddly enough, could be seen at least as a step in the right direction - the problem of course being that if you're going to take care of all potential liabilities, the total bill might be in tens of trillions, rather than mere trillions - with a lot of that money going to the smart hedge funds that bet on things going badly in various markets and for various institutions (cf Pauslon above).
Given all that, we have several routes:
* one that gives a lot of money to banks that do not deserve it to solve their asset problem, but still do not make them creditworthy (the current Geithner plan), which gives stock markets a temporary boost, taxpayers permanent pain, and solves nothing;
* one that does help them get rid of their real problem (huge contingent liabilities on bets that are turning sour), but is vastly more expensive than the mind-numbing numbers we're throwing around already, and gives all the money to hedgies: the AIG route, multiplied ten or hundred-fold;
* one that acknowledges that the issue is liabilities rather than assets, and that focuses on the fact that a lot of these liabilities are wholy unrelated to any economic or financial activity, and are contingent rather than actual - ie nobody loses anything if they are cancelled. If a 100:1 bet you made is cancelled, your actual loss is not 100, it is 1 - something that could be paid back to you.
So far, the second route has been used when an emergency beckoned (AIG et al); the first route has been used massively but the Treasury does not seem tired of it yet, and the third one seems anathema.