Pardon me for being facetious but the possibilities are endless. Carbon has a remarkable ability to #"catenate"#. What does #"catenate"# mean? It means the ability to form long chains. And along the chain there can be sites of unsaturation (i.e. double or treble bonds), as well as the possibility of heteroatom substitution, i.e. #H, O, S, N, X#.
Of course, the links in the chain are generally #"methylene, i.e. "CH_2# units. The variety and diversity of carbon chemistry is mind boggling. And what nature does in a big way, chemists can copy and try to emulate, and they can even innovate.
Carbon will also bind to transition and main group metals.