Just got the game Monday, enjoying the heck out of it. I especially like random stuff that happens when you're just wandering around.
A few I found amusing -
A wolf taking out a wild goat.
A couple of A'likr warriors I had just had a talk with on the road taking down a (different) wolf that was about to attack me.
I watched from a good distance the four guards of a Bandit fort that I was going to invade stupidly leaving the safety of a fort to attack a nearby Giant that was minding his Mammoth and his own business, and consequently getting wiped out, saving me the hassle of doing it myself.
Any of these kind of amusing random happenings that you witnessed you'd care to share?

Ive seen plenty Wolf vs. Horker battles. Wolves win 9/10 except when horkers have enough warriors.

I was talking to the 'Old Orc' who wonders around outside Whiterun after you hit a certain level. He talks about wanting to die because he is too old to be Chief and is useless as a warrior. Then out of nowhere, right after the Orc says he wants to die, a Giant comes up from behind and one-hit kills him. Irony at its finest.

It was right after killing a dragon outside whiterun, somehow the dragon lured the Giant over and he must have just finished killing guards then came after us.

A troll was killing some horkers, then a dragon comes and fights with it, one horker dies and one runs away, leaving the troll and the dragon fighting. the troll's health is low, so he comes running towards me and starts attacking me, so the dragon and I take down the troll. After that the dragon starts attacking me, so I run into a nearby dungeon (that happened to be where my current quest was).

Also, a giant got in a fight with a bear (might've been a saber cat), then a frost spider came and they had a three way dual, it was cool to watch.

I walked out of a house at night and right outside the front door was a freshly dead dragon laying on the roof of the house across the street. I walked up, absorbed the soul, looted it, said "thanks" and was on my way.

There's a point in the college of winterhold questline where you're crawling through a dungeon full of mages, and come across 3 or 4 vampire mistwalkers in cages. I like setting them free and then just watching, it's in a perfect spot right next to a couple of rooms full of mages, so the vampires go charging off and a huge battle ensues, with elemental spells going off everywhere and corpses resurrecting left and right.

Took a cart to a city (forget name) and when I got off the cart saw a dragon in the process of attacking it and setting houses on fire!

I was tempted to get back on the cart and say, "Return journey please, driver!"

During the college quest aftermath I was supposed to repair the rupture by destroying a few magic anomalies. Since it's a Radiant quest the anomalies spawn in random locations, this time around was the tundra, by the time I got there a pack of mammoths were already fighting the anomalies, so I just sat and wait.

From a distance, I saw what seemed to be a couple of bandits from their nearby fort attacking a mammoth. A passing dragon evidently thought the mammoth would make a good meal, and attacked it, being attacked by the bandits in turn. Then some of the bandits' comrades left their nearby fort to help. By the time I got close enough to join the fight, all of the bandits were killed, and I finished off the dragon. The mammoth survived to plod away (I'm still wondering why no giant was nearby). After looting the bandits, I entered their fort, where I found ample evidence that they liked to eat mammoths...and also encountered one last bandit, evidently the smartest of the bunch, who had elected to stay behind instead of getting slaughtered by the dragon. That probably represents the most loot for the least effort I've gotten in Skyrim so far, as well as some of the most entertainment per minute.