I have an IRA at E Trade. When a previous colleague of mine started his own company and looking for angel money, I provided an investment into his LLC with some cash of my own, and then an investment from my IRA. This way I was able to diversify my risk with cash and funds that I don’t have access to for a number of years. E Trade acts as the Custodian, charges me an annual fee, and prepares a tax return for me based upon the K1 that the IRA receives. They have since stopped providing this service, but the annual fees are low so I haven’t looked to transfer the investment to another custodian.