Could mating/recombination be responsible for evolution of entirely novel features?
Could the unison of such divergent sets of alleles theoretically lead
  to unique phenotype and features that bear little resemblance to any
  features belonging to the parents?


Though it is possible that some unique characteristics may emerge but it is very less likely that the offspring will bear no resemblance to the parents. You start with an example of humans. In this case it is, in my opinion, very unlikely because there is not so much of genomic diversity yet that may lead to such an outcome as you ask about. 

Some examples exist, such as the liger (offspring of a male lion and female tiger) that is bigger than both the species. This happens because of improper growth regulation because of interspecies differences. This could happen because the divergence between lion and tiger is much more than the intraspecific variations. 

Just a speculation : perhaps the offspring of H.sapiens and H.neanderthalis could have had such a feature but it seems unlikely for the current population of H.sapiens