Single family rentals (SFRs) which cash flow. I put 20%+ down on properties in solid locations (strong population/job growth, safe neighborhood, etc.). I save about 80%+ of my after-tax income.
I second the Single family rentals (SFRs). Follow the 12% rule which is that the house HAS to rent on an annual basis for at least 12% of purchase price. For example a $100K house has to rent for at least $12K per year ($1000/month). So put 20% down ($20K), get a 30 year fixed for $80K. Your expenses on monthly basis are mortgage + prop tax + prop manager + prop insurance = $500-$600. Rental income = $1000 per month. So you clear $400-$500 per month ($4800-6000/year) per rental property. With 20% down ($20K), that's a ROI of right around 20% before any property appreciation. Note: I didn't include closing costs which fluctuate a fair bit depending on lender and where the property is.
Doing a web business "on the site" is definitely very hard. However, you could invest money into highly tech startups, so that it balances your "old money" ;-)