A friend and myself run a tutorial blog for a hobby that makes us a very minuscule amount of money via AdSense. It's a nice extra incentive to push and grow the blog farther and farther along though.
In light of the current drama surrounding AdSense (fabricated or not), and in complete seriousness, what are some alternatives in case we randomly get "shut off"? We have used and are currently using BuySellAds and their Unreserved Program - which depends on a buyer though.
An ideal setup is one in which you utilize about a handful of different companies in the "Tier 2" position. Probably no more than a handful though, because after that it gets hard to manage and rather convoluted.
Tier 1 is your directly sold ads (stuff you sell on your own directly to an advertiser or through a company like BuySellAds).
Tier 2 is where the AdSense's of the world will live. It really depends on your "niche", but in general the best options tend to be: AdSense, Rubicon Project (if you're big enough), PubMatic (again, if you're big enough), or a "niche/vertical" ad company that focuses on sites like yours. By-and-large, AdSense "owns" this space outright, and even if you're using a program like ours (http://buysellads.com/publishers/unreserved) for your "non-reserved" inventory (stuff that isn't sold direct) there's going to be SOME mix of AdSense (or AdX) in there.
Ad money certainly isn't easy, and more and more is going to go toward those publishers creating great content and curating high-value audiences (i.e. not user generated content...). The days of "set it and forget it" are over for most publishers who aren't interested in earning pennies on the dollar. If you can't sell ads directly through a service like BuySellAds or on your own, well, I wish you luck :)
It's not all doom and gloom though - we see publishers make quite a bit of money all the time. It ultimately comes down to the quality of their site, it's content, and the users.