The Libor scandal seems to be waking people up to manipulation and fraud by the big banks.

There are many other types of fraud they've engaged in as well ...

Here is a partial list:

Pledging the same mortgage multiple times to different buyers. See this, this, this, this and this

Cheating homeowners - especially veterans - from laws meant to protect people from unfair foreclosure

Engaging in mafia-style big-rigging fraud against local governments. See this, this and this

Bribing and bullying ratings agencies to inflate ratings on their risky investments

Pushing investments which they knew were terrible, and then betting against the same investments to make money for themselves. See this, this, this and this

Engaging in unlawful "frontrunning" to manipulate markets. See this, this, this, this, this and this

Engaging in unlawful "Wash Trades" to manipulate asset prices. See this, this and this

Otherwise manipulating markets. And see this

Shaving money off of virtually every pension transaction they handled over the course of decades, stealing collectively billions of dollars from pensions worldwide. Details here, here, here, here, here, here, here, here, here, here, here andhere

Participating in various Ponzi schemes. See this, this and this

But at least the big banks do good things for society, like loaning money to Main Street, right?

Actually:

The big banks no longer do very much traditional banking. Most of their business is from financial speculation. For example, less than 10% of Bank of America’s assets come from traditional banking deposits. Instead, they are mainly engaged in financial speculation and derivatives. (and see this)

The big banks have slashed lending since they were bailed out by taxpayers ... while smaller banks have increased lending. See this, this and this