I mine Gridcoins. They're not currently traded on any exchanges but I imagine once they catch on they will have some value.
The reason being, they are tied to BOINC. The Gridcoin wallet verifies that you're working on BOINC projects and trickles coins to you as a reward.
I don't even need to run the dedicated mining tools to get some coins on the side. I just work on the research projects that BOINC is dedicated to and the coins add up.
Is it worth anything right now? Nope. But it might be in the future. And it's a reward for contributing to real-world research, not just verifying transactions.
That's the kind of coin I think will have a future. Ones that are tied to tasks of value, rather than just a clever name and a pump and dump scheme.
I've been hoping to see a coin for Render Farming as well. It would be great to be able to dedicate CPU time to works, earn coins, and either sell them off to people who want them, or use the coins within the system to buy higher priority when rendering out animations.