It would be cool to not contribute to the obscene amount of new cryptocurrency spawns and instead work to upgrade existing ones with newly imagined features. But, if the newly imagined feature/altoin is truly valuable, original and irreplaceable with any existing altcoin, it would have merit to spawn a new one.
If designing a new altcoin, consider following the footsteps of Gridcoin and Curecoin. Especially Curecoin: it seems to be a hybrid between centralized and decentralized system, it uses centralized tracking to issue rewards in proportion to points obtained in particular distributed computing project (F@H) and is also a hybrid POS/POW coin which can also be regularly mined and obtained. You could copy its model to other distributed computing medical research or science projects (other than F@H). Combine it with something like this:
http://www.wired.co.uk/news/archive/2014-02/24/htc-power-to-give (smartphone based pseudo-supercomputing) and you have a potential to have whole Africa mining coins with cheap smartphones while contributing CPU/GPU cycles to useful scientific research and earning something in return.
Also, one crazy idea is to have some kind of consolidation of very similar "shit coins" in some form of fusion in one new "chimera coin". You'd have to merge chains, wallets, logos, coins, names, everything, in order to fuse 2 or more shit coins to form a brand new chimera. It seems like one would have to be very skilled to accomplish something like that, implying a person who would probably not want to be involved in somewhat frivolous activity of that kind.
Also, it seems there is a vacuum of cryptocurrencies which explicitly address, explore and embody non-implemented aspects of security against potential emergence of powerful quantum computers. Ideally, they would combine all the techniques considered in
https://en.wikipedia.org/wiki/Post-quantum_cryptography.
