When I first started Mac OS X development, and later iOS, interface Builder and Objective C were a revelation. To this day, “NS” (for NeXTSTEP) prefixed classes can still be found in the mac frameworks. The company may have ‘failed’, but the ideas succeeded. (And given how much Steve’s companies were an extension of himself, ‘failed’ is subjective here — in the end, it was through NeXT that Jobs won back Apple.)