I would say that not many actual implementations of software turn out to be beautiful, assuming it is above a certain threshold of complexity and it is meant for production use.
On the other hand, the ideas, algorithms, or the protocols on which software is based often seem beautiful, elegant, or brilliant, at least to me.
A few examples I can think of are: Google PageRank algorithm, Bitcoin's protocol and the block chain, the TCP network protocol, the BitTorrent protocol, Dijkstra’s algorithm, etc.
I respectfully disagree. Many of the elements of tcp are very complicated, and more or less of a hack. Compose them all together, and it's a hugely complex and arguably ugly (if utilitarian) standard.
On the other hand, the ideas, algorithms, or the protocols on which software is based often seem beautiful, elegant, or brilliant, at least to me.
A few examples I can think of are: Google PageRank algorithm, Bitcoin's protocol and the block chain, the TCP network protocol, the BitTorrent protocol, Dijkstra’s algorithm, etc.