Manual of Buddhist Terms and Doctrines, by Ven. Nyanatiloka. A handy reference for Buddhist terms, Pali and English, with quotes from the original texts.
Edited by George P. Malalasekera, London, 1937-38.
This comprehensive reference covers all proper names one will find in the Pali canon and primary commentaries. It provides sufficient information to place each proper name - physically (or mythicly) for place names, in time and school of thought for individuals. It provides the references to the source material, and etymologies where appropriate.
For instance, if you are searching for all Pali compounds ending with the word "...kamma", you can easily find all these words on one page in this reverse dictionary.
This dictionary can be quite useful in looking up the meaning of some Pali words, if you know how to find the Sanskrit counterparts of Pali forms. The on-line version of the dictionary is available at http://www.sanskrit-lexicon.uni-koeln.de/scans/MWScan/tamil/index.html .