If you can specify which location you are looking for, i am sure some realtors from that location might be able to help you look that up.
If not, go to http://www.Realtor.com, click on Find a Home, enter the city, state and then click on Advanced Option right next to the Search button, and look for multi-units.
However, even with single family residency, if you read the description carefully, it might say that it has a guest house or mother-in-law quarters. Now a days, some homes have two master suites or 2 story homes will have a separate guest suite downstairs and master suite and other rooms upstairs; these are all your options.
To save the work, look for a reputable Realtor in your area. It is a Realtor's job to know the local properties and market condition, it is also their job to interview their clients and look for the right house for their clients.
Best of Luck,
2. Get an agent. Agnets have access to better and more qualifying information than the general public, even with all the web real estate sites. Agents can search expired or withdrawn listings and may be able to find you something that is not even on the market.