I've toyed around with a few radical thoughts recently, but political ideology isn't my bag so it's just private speculation.
One is that the problem with socialist schemes is that they don't really address the root of inequality. It's become kind of clear to me that the root is heritable inequality of both the genetic sort and the inherited-privilege sort.
So I've speculated a little about some sort of "transhumanist socialism" that would attempt to address inequality at the biological level by making both germ-line and postnatal enhancements universally available. The idea would be to transform humanity itself into a runaway self-improving AI by siphoning off some percentage of GDP and applying it to the artificial redistribution of beneficial adaptations and the augmentation of human intelligence across familial lines. By far the best thing to be taxed here would be inheritance, since the whole aim is to break heritable inequality.
It's the sort of idea that would make everyone's head explode. Most dogmatic libertarians would hate it since it contains the word "socialism" and involves some sort of wealth redistribution. Liberals are all greens now that worship the naturalistic fallacy, so they'd all scream "no GMO!" Conservatives would hate it since it's theologically sacrilegious and would disrupt the social order rather deeply.
Makes me think I'm on the right track. :)