I keep some cash in a savings account, and some in VTI, but recently I started allocating some to Lending Club, investing in the "safer" A and B loans, without doing automatic re-investing.
Of course, your money is not liquid, but you still receive interest payments every month, so there is some cash flow. To me, it's a (riskier) way to try to get 4%-6% return on some of my cash that is otherwise barely earning anything.