A recent publication describes CovBinderDB DOI is a fantastic resource mined from the PDB that contains 7375 covalent modifications in which 2189 unique covalent binders target nine types of amino acid residues (Cys, Lys, Ser, Asp, Glu, His, Met, Thr, and Tyr) from 3555 complex structures of 1170 unique protein chains. The database can be accessed here https://yzhang.hpc.nyu.edu/CovBinderInPDB/.

I've added it to the Covalent inhibitors page of the Drug Discovery Resources.