What about hidden services? In my opinion that's the real heart of Tor. I think the value of exit nodes will start to wane as Tor gains a larger and larger user base and becomes it's own truly viable darknet. As it stands the majority of security related discussions I've come across regarding Tor strongly discourage spending any large amount of time on clearnet services anyway as this create many potential security/privacy risks.
If you are more interested in the hidden services aspect, did you also have a look at I2P [1]? It is more geared toward this aspect (exit nodes = outproxies in i2p-speak for example are just standard hidden services)
