What is your favorite example of speciation?

I still think that Darwins Finches make an excellent demonstration of evolution. Different species have different beak shapes in order specialize on different food sources.What is nice about this is that many of the species can hybridize. These hybrids are less well adapted than their specialized relatives and when climatic conditions are bad the hybrids are observed to die off faster.So not only can this show that several species are adapted to suit their particular ecological niche you can also show that hybrids are less well adapted. Because hybrids are less adapted you can also tentatively conclude that in the past less adapted ancesters evolved into better adapted species.Hopefully I am making sense, though I'm not a trained biologist.Also there are plenty of examples of plants adapting to high Lead concentrations next to roads and highways. In many cases the plants actually require high lead concentrations to thrive. This has started to reverse as many/most countries have banned lead additives in gasoline and the lead concentrations near roads has dropped.

Thanks for the correction. Are the Darwins Finches considered as speciation? I have read that hybridization occurs (and that hybridization in closely related bird species is common).One definition that I have seen of what a species is of a population of living organisms that can only interbreed with itself. Clearly this definition is insufficient to account for the many organisms that can hybridize.