Of course, cimbaloms vary a bit between countries and regions. And though they aren't the same thing as a Hammered Dulcimer (at least, as it is known in British and American folk circles), they are sometimes referred to as Eastern European Hammered Dulcimers, and some cimbalom libraries are just called Dulcimer, such as the one from Cinesamples World Series.
Dennis at Bolder Sounds was probably the first to deep-sample several cimbalom and hammered dulcimer models, for Kontakt. Since that time, UVI World Suite has added somewhat more detailed patches for Hungarian Cymbalum and Moldovian Cymbalum.
The Spitfire Cimbalom is my top choice for the past few years, but I think it's the one that got repackaged for the Originals series and I haven't been terribly thrilled with the non-Kontant versions of things from them.
I would love for VSL to do a cimbalom or two. I have some arrangements in mind, that I have sketched roughly without fleshing out as I'd rather wait until there is a top-tier library available to render them.