I do like this idea, but I'm a bit skeptical that a relic of the 1930s would work in our modern economy. Thus, I suspect the answer is a bit more complex than "Bring back Glass-Steagall".
I think the economics is pretty timeless, actually. A lot of the regulation was aimed at preventing catastrophic bank failures, before the idea of Too Big To Fail was invented. Glass-Steagall contains the idea that a commercial bank, which gets major regulatory freebies by virtue of being a commercial bank (FDIC, Fed access, &c), shouldn't have access to unfettered financial markets. And so on.
Go and read J.K. Galbraith's The Great Crash: 1929. It's a short book, an easy read, and quite informative. Particularly interesting is his examination of causes and ramifications. If you buy a recent edition, these have been updated through the 1960s and 70s, with a foreward by his son in 2009 (the book was first published in 1955).
Though the situation of the 2008-2011+ crash/depression isn't an exact reflection of 1929, there are very strong rhymes.
