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 tones of results. I have heard that trailer 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 dogs 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 therory 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 tippy, also the dog may try to jump out causing a crash.