Polymer networks derived from furan monomers are discussed, with particular emphasis on recent contributions. Resins based on furfural and furfuryl alcohol represent the most important family within this context, but other materials are becoming relevant, such as polyurethane foams, various photo-curable macromolecules bearing furan rings within the chain (or pendant to it), conjugated cross-linked poly(2-vinylfuran) as proton traps, and thermo-reversible networks prepared by Diels-Alder polycondensations involving furan and maleimide moieties.