I would advise against anything like angel investing. You're not in a position where liquidity concerns wouldn't pop up, so having access to your money (should you need it) is important. Angel investing means tying down your cash for years...

I personally suggest you follow Nassim Taleb's advice (he of Black Swan fame), which you seem to be doing by keeping the majority in conservative,safe investments and looking to score big with the remaining. If you're looking for home-runs, I suggest options trading. There's a lot of volatility in the market, and if you time things right you should be able to generate a handsome return.

Good luck!