The only real alternatives to AdSense are the top tier CPCs - Burst, Casale, TribalFusion and, perhaps, the new Yahoo/Bing option whose name I forget. Unfortunately, you'll need serious Tier 1 traffic to get into any of those (several million hits a month) and they don't take all types of site.
Putting those aside, the best alternative was adBrite before it went out of business. They had a lovely CPM/CPC mix setup that generated a reasonable amount of cash. With them gone, you're left with an enormous pile of cheap-ass CPC and CPM providers who provide very little return compared to Google, but whose programs are pretty easy to get into.
Names that spring to mind (i.e. I've tried them) are Chitika (which sucks), Infolinks (haven't tried them, actually), Komoona, Lijit, CPMFun, CPMGo, Popads, Juicy, Qadabra and a ton of others. The only ones which pay decently are those offering pop ads (whether under or over), since that's an expensive medium: everything else pays 10-20c per thousand views or less than a cent per click.
The moral of the story is "don't lose your AdSense account... or learn to use CPA ads".