One modern tycoon in the computer technology arena would be Bill Gates. By coming up with a widely-adopted operating system, Gates helped build Microsoft into a massive and incredibly powerful company that maintains a huge market-share to this day. Just like Carnegie and other tycoons, he has used every possible advantage to build the company and strengthen the bottom line. This is not just limited to pushing research and development but also includes lobbying efforts to gain advantages through legislation and protection or to fight off competitors.
Like those tycoons, Gates has also tried to find positive ways to use his wealth to benefit society, the largest effort being the Gates foundation into which he has poured billions of dollars to benefit education and other public-welfare causes.
A "tycoon" from the modern entertainment industry could be Jay-Z. He's been an innovator and massively successful and used one success to lead to the next by branching out and strengthening his brand. He too has tried to find ways to be charitable, and sometimes seems to match his charitable efforts to perceived arrogance or other public relations problems.