Estate taxes have a tendancy to hit farmers very hard as they tend to be land rich and cash poor. Capital gains I am all in favor of, but taxing investment income too heavilly tends to contribute to unemplyment. Of course luxury taxes are also an old standby- cars worth over $60,000, Yachts, houses wourth over $450,000, etc get extra taxes applied...
of course another aspect of the question is why you really want wealth equality vs. income equality or standard of living equality. Right now the wealth tends to be concentrated into the hands of people who have made a profession out of managing it- redistributing it could easilly lead to less effective management, or you get issues like prefered stock versus common stock, and of course when you encourage people to invest without understanding tehir investments you get Bernie Maddoff and stock market crashes... there was an old stock trader who pulled everything out of the stock market right before the crash leading to the great depression- my great grandfather asked him how he knew and he said he knew it was time to get out of the market when he got a stock tip from his shoe shine boy. Because once teh amateurs were getting heavilly invested the whole thing was going to go sideways.
Kind of like when congress decided to incentivize loans for low income home ownership and teh subsequent effects on teh real estate and credit markets.