This review describes the design of extensively conjugated electron donors and acceptors based on structural modifications of tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ), respectively. These molecules have the advantage of reduced on-site Coulomb repulsion which is one of the prerequisites for components of organic metals. The construction of such large compounds is currently accomplished by insertion of an extensively π-conjugated system between two 1,3-dithiolylidene or dicyanomethylene groups. The usefulness of a heteroquinoid system as such a building block is demonstrated by examples of heteroatom-incorporating TCNQ acceptors (hetero-TCNQs), which form a variety of highly conductive charge-transfer complexes. In addition, recent advances concerning quino-2,2′-bis(1,3-dithioles) and TTF vinylogs as novel electron donors are introduced.