We have something like that in Canada. It's called Tax-Free Saving Accounts. They are registered accounts (like 401k or IFA) but you can take out the money at anytime without penalities. The money you put in is after tax (unlike 401k and IFA) but all the growth is tax-free both on-going and when you take it out.
It can be invested in pretty much any financial type investment (stocks, mutual funds, bonds or mix of it).
So for example if you wanted to save money for a house, you put money in there, it grows tax free and you can take it out when you need it (tax-free)
There is a limit of how much you can put in (5000-6000$ per year since the program started).
It's a very nice complement to traditional retirement saving since you don't have to wait for retirement to take it out.
While obviously it not for everyone, even people with more limited income can benefit from it. And since the limit is not percentage based but hard number, it only marginally benefit the ultra-rich.