[jethroalias97]

What would be interesting is if there were real online bitcoin banks that leant or invested the bitcoins to both make a profit themselves and offer their customers some interest on their savings.

[wmf]

I heard there's one called Bitcoin Savings & Trust.

[javert]

Jokes aside, there are a number of people doing this "for real" (or at least, "not obviously a ponzi"). They can be found on bitcointalk.org.