Gridcoin is the biggest I'm aware of. Most people who mine it (that I've spoken to) think of it as a way of subsidizing their hardware and electricity, not as a get-rich-quick scheme. Since it lets you choose what project to work on, you can choose one that you approve of and that is well-suited to your hardware.

I was considering buying some old servers to mine it. I'd have pretty much broken even back when it was $0.10/grc, but it would have taken me ages to make back my investment.