Do "Tramp" Steamships Still Operate?

In today’s world of 500,000 ton containerships, it would seem that the pre-WWII “tramp” steamer wold be an anachronism. A “tramp” was a small cargo ship that had no fixed schedule-it would call at various ports, take on cargo, and head to the next port. They were a popular item in fiction-a stranded American in China cold always get home by signing on as a crew member. (Richard Halliburton traveled the world this way).
Do such ships still exist? Can you book passage on them?

Wikipedia claims they still exist:

I have no idea if you can still negotiate cheap passage on one.

Good Lord, evidently you can: