I thought you might like to hear about my Guide Dog, Dodger, who is an Irish Water Spaniel crossed with a Golden Retriever.  He is from the first litter that Guide Dogs have tried, and they seem to be very successful.
I have attached a couple of photos for you to see him.

He is two years old, and is jet black, apart from some brown on his front paws. He has a wonderful temperment, and is an excellent Guide. 

His favourite pastime, when he's not working, is diving in the river. He gets a lot of attention from people wherever I go, and has been mistaken time and time again for a labradoodle, and a poodle, but two people actually got the IWS bit right!  He weighs just over 80 pounds, so is probably a little larger than the average IWS.
 
Dodger may not qualify for your site not being a pure breed, but I thought your readers, might be interested in seeing him.