The most widely-known way in which humans have intervened with other species has to be through genetic maneuvering and alteration.
For example, genetically-modified crops are thought to be the answer for world hunger because the process of genetic modification allows scientists to use the strongest genetic qualities of a species of plant in order for it to produce bigger, better, or more nutritious fruits and vegetables.
Animals have been bred for centuries and new species of dogs and cats have evolved as a result of that form of breeding. That could be another human intervention that has aided in the evolution of some species.
However, think about stem cell research and how using human cells and genes can be useful to the future cures of cancer and other diseases. That is major human intervention in extending the lives of a species known as Homo Sapiens. Those are just a few to think about. Other than that, as the first law of physics states "Matter cannot be created, nor destroyed." Therefore, we cannot build the next Frankenstein, nor clone the next Michaelangelo. Well, clone them, maybe- but not create them.
Hence, we can boast that humans have, indeed, aided in the perpetuity of some species, and the betterment of others in several of the living kingdoms that coexist in our planet.
Yes, there is...
Nylon is a synthetic product. It does not exist in nature. It was developed in the 20th century. In 1975, Japanese scientists found bacteria which had evolved to digest nylon, living in the waste water of a nylon factory. It is an example of modern speciation caused by man.
While the breeding of dogs can cause a wide variety of change in the appearance and/or behavior of the animal, it has not created a new species. A dog is still a wolf. The same could be said for other domestications.
Can genetic splicing cause a new species to form? Possibly, but to my knowledge, it hasn't been done. I would love to see any links anyone might have, though.