In a campaign I was in a few years ago, I was a desert ranger. To take a bunch of softy city folk through the desert, we bought camels and had them pull our wagon. Naturally we got into a fight with giant scorpions.
The camels kicked more behind than our 1st and 2nd-level characters... well, if it wasn't for the -5 penalty to hit they would have. They did help us flank the scorpions, which enabled one of them to hit for serious damage, too.
Afterwards I was so impressed I tried to make one of the camels my animal companion* but it didn't work out. Later on I switched to the Iron Kingdoms ranger, who doesn't have an animal companion. Furthermore, we ended up in a forest and then a city, where camels would have been a hindrance.
*It would no longer have the -5 to hit penalty.