Investing in Index Funds – I use Vanguard for this, but there are several reputable sites out there that allow you to do the same thing.  It’s a good way to invest excess cash that you don’t need now and use it to diversify your portfolio.  I’m not going to make a specific recommendation here, but Vanguard does have a page that will make a recommendation to you based on your risk tolerance.  This is generally going to require more up-front money than Lending Club (probably $1,000+), but if you have the money, it’s something to consider.

I see you include rental income, e-book sales and P2P loans as part of your passive income. Do you not consider your other internet income as passive? Is that why it’s not in the chart? Or did you not include it because you would rather not reveal it at this point? (I apologize if this question was already answered – I didn’t read through all the comments, and it’s been about a week since I actually read this post via Feedly on my phone)
Portfolio income can come from multiple sources – interest/bond coupons, stock dividends, financial strategies including derivatives and capital growth.  Each offers some cash flow and some also offer potential capital gain with some risk from liquidity and volatile prices.  In this low-yield environment, many investors rely too heavily on cash flows and to pursue this are venturing further into riskier areas than they’d normally consider.