We had a customer pick a 16ft fishing boat up and towed it away in a bright yellow Saab 93. Was certainly eye catching. I've seen mk1 mx5s with type bars, but my wifes mk3 isn't allowed one. I think everything need type approval now so can't just stick one on anything.
My Volvo C70 D5 came with a towbar fitted, I've used it for a bike rack but I've often thought it'd be a great tow car. I personally prefer automatics for towing though.