Just some thoughts I have on this topic:
I was renting a room in my house in Ohio for 500/month. The insurance company recently raised my premium and my property taxes went up slightly so my mortgage went from 480/month to 550/month (yeah I'm shopping around for better rates). But basically until my roommate moved out, I was living almost rent free, I only covered the utilities.
It was a pretty good experience for me and a socked away a lot of extra money every month, granted I didn't rent the whole house, just a room and I was around a lot to see what was going on. Furthermore, my roommate and I were/are good friends so I worked out fine, he was my sim partner from a previous regional carrier (we shared a hotel room for 6 weeks) so I could trust him. I'd be VERY leery about putting up an ad on craigslist, especially since I'm gone half the month.
If I rented out the entire house in my neighborhood, I would get around 750-850/month (its a 2.5 bedroom/1 bath). I'm actually considering doing that now so I can move back to Florida. But the house will require about $3000 worth of work to get to the point where I can rent it to a family and be up to code. It's in good shape but probably needs to be re-shingled, needs GFI outlets installed in the kitchen and bathroom, new carpet upstairs, and other minor stuff.
That said, if I do it I would recommend a property manager if your inexperienced at renting out property (like me). The ones I talked to in Ohio charge first month's rent (to find the tenant) then 10% of rent per month after that. I'm not sure if that's market price?, (I need to do more shopping around) but the one I talked to said she'll find tenants, check on the property regularly, be the one that gets called bc the basement flooded at 3AM, and take care of evictions if necessary. After the mortgage, taxes, insurance, property manager, and MX costs I don't think I'll be making more than $50 cash per month, but its free equity.
So its not quick money, if you can buy into a dip or put a lot down on a house that's move in ready you may be able to make a decent amount extra per month after rent. But, I still feel its a better way to go than a lot of the mutual funds/IRAs/etc out there, and you have much more control with what is going on.
MORE EDITS: You can deduct any repairs, appliance purchases, management fees, mortgage interest, and cleaning fees against the rental income from the house making it very tax advantageous. But, you need to own the property for two years or more before you sell (and make less than 250K profit on the sale) OR you have to pay capital gains tax. So basically, plan on owning the house for at least two years.
Also, when I talked to the bank during the purchase process 2 years ago I was able to qualify for an FHA loan (3% down but I have to pay PMI), but these loans are not available for pure rental property (I'll probably have lived in the property for at least 3 years before renting it out). I plan on using a VA loan to purchase property in Florida in the next 2-3 years, but again I can't it use as rental property.
Good Luck.