How do you carry a dog on a bike? Over the years I have seen a few people transport a dog on a bike.  What options have you seen?   Please include a photo in your answer if possible.
I just googled "Bike Dog trailer" and got tonnes of results.  I have heard that trailers from "WIKE" are good.  Here is a pic of their biggest dog trailer: 



I have also seen a few DIY dog trailers.  

I like this quite a bit.  The dog is just tied in so they don't jump around but they still get a good view.  Found at Bike Trailer Blog



There is also the option to mount the dog's crate onto the trailer.  I have seen lots of pictures of these. Basically you just need to put some bolts through the flatbed of the trailer. This is a more professional example from Tony's Trailers: 



I guess in theory you could also put a small dog in your front basket, but I would not do that.  If the dog moves around that will make your bike unstable, also the dog may try to jump out causing a crash.