The NIST Chemistry Web Book (http://webbook.nist.gov/chemistry) is created by the National Institute of Standards and Technology. It is a great source of information about thermochemical properties of small organic and inorganic substances, and it also contains a table of constants of diatomics based on those found in Herzberg's Molecular Spectra and Molecular Structure.
NIST is searchable by formula, name, and structure, as well as CAS Registry Number and InChI. A formula search for this type of substance is usually very effective.
One of the nicest features of the NIST Web Book is that it links out to other information available on public NIST sites. One of these, the Computational Chemistry Comparison and Benchmark Database, has a number of interesting properties, including atomization enthalpies. Note that this option may not exist for every substance.
The CRC Handbook of Chemistry and Physics contains nice tables of BDEs for diatomic molecules, gaseous atoms, polyatomic molecules, and more. They are located in Chapter 9, beginning on p. 65. You can access the CRC Handbook either in print in the Chemistry Library Reading Room on online. If you want to use the online version, please follow these steps to zoom directly to the table in question.
