Hi @Patrick Hayes, I'm actually doing a Webinar on 8/10 with an IRA Custodian on this very subject.

Often they lend their self-directed IRA funds.

No entities are allowed to originate loans post Jan 2014 unless it's your SD-IRA.  

IRA's are "usually" hosted with a brokerage and you can buy various publically traded securities, e.g. mutual funds, ETF's, stocks, bonds, etc.If you setup your IRA as a "self-directed" account which allows slightly greater options, such as forming a LLC owned by the IRA (something like that), you can then have the LLC invest the IRA's funds in such investment as a rental property.Again, hopefully you see that you are getting tax deferred growth, of one more or another. 

I have a checkbook IRA in an LLC and ready to purchase a property.

I'm in the process of talking to financial advisor on how to roll over an old 401(k) into a self-directed IRA or solo 401(k), so I can invest in real estate and promissory notes in a retirement account. 

From real estate sales, wholesaling, flipping, rentals, lending, self-directed IRA and Solo 401k investing, or tax and legal guidance, you will find that many members here are very knowledgeable in their respective fields.

Also, if/when you begin to get into purchasing with IRAs or 401Ks, you cannot participate in the sale of the property.

So far my rentals are in my SDIRA, and what I am looking for there is a better return than stocks and more stability over the long run, and also just the diversity of keeping some of my IRA in stocks and some in real estate.I have been talking to a few different people that are somewhat interested in working together in some way.

Also - if anyone use a self directed IRA to buy properties, can you roll an existing IRA or 401k into this new tax shelter shelter?