Namecoin introduced the database-in-the-blockchain setup, with use as a kind of DNS as its example application for such data; and it also introduced Merged Mining.

I0Coin, one of the SHA256 merged mined coins, introduced fixes for the massive-RAM-use problem that family of merged mined coins were all eventually going to notice; the others, maybe including namecoin maybe not I am not sure, adopted those RAM-usage fixes from I0Coin. (Not sure if namecoin addressed that problem yet or not.)

Oh and also, of course, DeVCoin (DVC) introduced a whole new way of distributing minted coins. (Initially to authors of free open-source software, later also to authors of free open source writings (see Devtome), eventually intended to branch out to free open source 3D printers and print-specifications, free open source spacecraft, free open source music, graphics, images and so on and so on...)

-MarkM-